The history of AI is a history of fantasies, possibilities, demonstrations, and promise. Ever since Homer wrote of mechanical “tripods” waiting on the gods at dinner, imagined mechanical assistants have been a part of our culture. However, only in the last half century have we, the AI community, been able to build experimental machines that test hypotheses about the mechanisms of thought and intelligent behavior and thereby demonstrate mechanisms that formerly existed only as theoretical possibilities.

– Bruce Buchanan [2005]

This book is about artificial intelligence (AI), a field built on centuries of thought, which has been a recognized discipline for over 60 years. As well as solving practical tasks, AI provides tools to test hypotheses about the nature of thought itself. Deep scientific and engineering problems have already been solved and many more are waiting to be solved. Many practical applications are currently deployed and the potential exists for an almost unlimited number of future applications. This book presents the principles that underlie intelligent computational agents.