The capacity to learn is a key facet of intelligent behavior, and it is no surprise that much attention has been devoted to the subject in the various disciplines that study intelligence and rationality. We will concentrate on techniques drawn primarily from two such disciplines—artificial intelligence and game theory—although those in turn borrow from a variety of disciplines, including control theory, statistics, psychology and biology, to name a few. We start with an informal discussion of the various subtle aspects of learning in multiagent systems and then discuss representative theories in this area.

Why the subject of “learning” is complex

The subject matter of this chapter is fraught with subtleties, and so we begin with an informal discussion of the area. We address three issues—the interaction between learning and teaching, the settings in which learning takes place and what constitutes learning in those settings, and the yardsticks by which to measure this or that theory of learning in multiagent systems.

The interaction between learning and teaching

Most work in artificial intelligence concerns the learning performed by an individual agent. In that setting the goal is to design an agent that learns to function successfully in an environment that is unknown and potentially also changes as the agent is learning. A broad range of techniques have been developed, and learning rules have become quite sophisticated.