Multi-Agent Systems

Decentralized Agents with Incomplete Information Working Together

Intelligent Assistants Working With You and For You

"The characteristics of MASs are that (1) each agent has incomplete information or capabilities for solving the problem and, thus, has a limited viewpoint; (2) there is no system global control; (3) data are decentralized; and (4) computation is asynchronous."
- from MultiAgent Systems, by Katia Sycara

Katia Sycara

The study of multiagent systems (MAS) focuses on systems in which many intelligent agents interact with each other. The agents are considered to be autonomous entities, such as software programs or robots. Their interactions can be either cooperative or selfish. That is, the agents can share a common goal (e.g. an ant colony), or they can pursue their own interests (as in the free market economy).

MAS researchers develop communications languages, interaction protocols, and agent architectures that facilitate the development of multiagent systems. For example, a MAS researcher can tell you how to program each ant in a colony in order to get them all to bring food to the nest in the most efficient manner, or how to set up rules so that a group of selfish agents will work together to accomplish a given task. MAS researchers draw on ideas from many disciplines outside of AI, including biology, sociology, economics, organization and management science, complex systems, and philosophy.


We want to build intelligent actors, not just intelligent thinkers. Indeed, it is not even clear how one could assess intelligence in a system that never acted – or, put otherwise, how a system could exhibit intelligence in the absence of action.

- Martha Pollack, from Computers and Thought Lecture, IJCAI-91

Authors have agents . . . professional athletes have agents . . . movie stars have agents . . . and you have agents too. Because an agent is someone with expertise who is entrusted to go out and act on your behalf, the computer programs that help you to maximize your computing experiences are called "agents". The next time that you search for specific information on the internet, picture your own agent or group of agents at work, with each knowing just what you're interested in and how important your time is.

Definition of the Area

"A coupling of perception, reasoning, and acting comprises an agent. An agent acts in an environment. An agent's environment may well include other agents. An agent together with its environment is called a world.

- Sec. 1.3 of Poole & Mackworth Artificial Intelligence: Foundations of Computational Agents (2010)

An agent could be, for example, a coupling of a computational engine with physical sensors and actuators, called a robot, where the environment is a physical setting. It could be the coupling of an advice-giving computer – an expert system – with a human who provides perceptual information and carries out the task. An agent could be a program that acts in a purely computational environment – a software agent. "


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