Intelligent Agents: The Key Concepts [chapter]

Michael Wooldridge
2002 Lecture Notes in Computer Science  
This chapter aims to introduce the reader to the basic issues surrounding the design and implementation of intelligent agents. It begins by motivating the idea of an agent, presents a definition of agents and intelligent agents. The article then goes on to discuss four major approaches to building agents. First, logic based architectures are reviewed, in which decision-making is viewed as logical deduction. Second, reactive architectures are discussed, in which symbolic representations and
more » ... s are eschewed in favour of a closer relationship between agent perception and action. Third, we discuss belief-desire-intention architectures, in which decision making is viewed as practical reasoning from beliefs about how the world is and will be to the options available to an agent, and finally to intentions and actions. Fourth, we review layered agent architectures, in which decision making is partitioned into a number of different decision making layers, each dealing with the agent's environment at a different level of abstraction. -When a space probe makes its long flight from Earth to the outer planets, a ground crew is usually required to continually track its progress, and decide how to deal with unexpected eventualities. This is costly and, if decisions are required quickly, it is simply not practicable. For these reasons, organisations like nasa are seriously investigating the possibility of making probes more autonomous -giving them richer decision making capabilities and responsibilities. -Searching the Internet for the answer to a specific query can be a long and tedious process. So, why not allow a computer program -an agent -do searches for us? The agent would typically be given a query that would require synthesising pieces of information from various different Internet information sources. Failure would occur when a particular resource was unavailable, (perhaps due to network failure), or where results could not be obtained. This chapter is about intelligent agents. Specifically, it aims to give you a thorough introduction to the main issues associated with the design and implementation of intelligent agents. After reading it, you will understand: -why agents are believed to be an important new way of conceptualising and implementing certain types of software application; -what intelligent agents are (and are not); -the main approaches that have been advocated for designing and implementing intelligent agents, the issues surrounding these approaches, their relative merits, and the challenges that face the agent implementor. The chapter is structured as follows. First, Sect. 2 describes what is meant by the term agent. Section 3, presents some abstract architectures for agents. That is, some general models and properties of agents are discussed without regard to how they might be implemented. Section 4, discusses concrete architectures for agents. The various major design routes that one can follow in implementing an agent system are outlined in this section. In particular, logic-based architectures, reactive architectures, belief-desire-intention architectures, and finally, layered architectures for intelligent agents are described in detail. Comments on Notation. This chapter makes use of simple mathematical notation in order to make ideas precise. The formalism used is that of discrete maths: a basic grounding in sets and first-order logic should be quite sufficient to make sense of the various definitions presented. In addition: if S is an arbitrary set, then ℘(S ) is the powerset of S , and S * is the set of sequences of elements of S ; the symbol ¬ is used for logical negation (so ¬p is read "not p");
doi:10.1007/3-540-45982-0_1 fatcat:fiazijq3yjacvnike7poaqtha4