Preface. - Introduction. - 1. Basics: The Modal Approach To Knowledge. - 2. Various Notions of Knowledge And Belief. - 3. Knowledge And Ignorance. - 4. Default Reasoning By Epistemic Logic. - A. Appendixes. - E. Answers To The Exercises. - R. References. - I. Index.

Epistemic logic has grown from its philosophical beginnings to find diverse applications in computer science as a means of reasoning about the knowledge and belief of agents. This book, based on courses taught at universities and summer schools, provides a broad introduction to the subject; many exercises are included, and solutions to them are given in a final appendix. The authors begin by presenting the necessary apparatus from mathematics and logic, including Kripke semantics and the well-known modal logics K, T, S4 and S5. Then they turn to applications in the contexts of distributed system and artificial intelligence : topics that are addressed include the notions of the common knowledge, distributed knowledge, explicit and implicit belief, the interplays between knowledge and time, and knowledge and action, as well as a graded (or numerical) variant of the epistemic operators. The problem of logical omniscience is also discussed extensively. Halpern and Moses' theory of honest nonmonotonic reasoning and preferential entailment. Moore's autoepistemic logic is discussed, together with Levesque's related logic of 'all I know'. Furthermore, it is shown how one can base default and considered alternative approaches to knowledge and belief, viz. Konolige's 'deduction model' and the 'knowledge structures' of Fagin, Halpern and Vardi, as well as a brief discussion of a first-order variant of modal epistemic logic, and a table of the basic logical systems. - Back cover.