The idea of kwledge bases lies at the heart of symbolic, or traditional, artificial intelligence. A kwledge-based system decides how to act by running formal reasoning procedures over a body of explicitly represented kwledge -- a kwledge base. The system is t programmed for specific tasks; rather, it is told what it needs to kw and expected to infer the rest. This book is about the logic of such kwledge bases. It describes in detail the relationship between symbolic representations of kwledge and abstract states of kwledge, exploring along the way the foundations of kwledge, kwledge bases, kwledge-based systems, and kwledge representation and reasoning. Assuming some familiarity with first-order predicate logic, the book offers a new mathematical model of kwledge that is general and expressive yet more workable in practice than previous models. The book presents a style of semantic argument and formal analysis that would be cumbersome or completely impractical with other approaches. It also shows how to treat a kwledge base as an abstract data type, completely specified in an abstract way by the kwledge-level operations defined over it.
Hector J. Levesque is Professor of Computer Science at the University of Toronto.