Title: On the Semantics of Knowledge Update

Authors: Chitta Baral and Yan Zhang


We consider the problem of how an agent's knowledge can be updated. We propose a formal method of knowledge update on the basis of the semantics of modal logic S5. In our method, an update is specified according to the minimal change on both the agent's actual world and knowledge. We then investigate the semantics of knowledge update and characterize several specific forms of knowledge update which have important applications in reasoning about change of agents' knowledge. We also discuss the persistence property of knowledge and ignorance associated with knowledge update.