Revision Specifications by Means of Programs

We propose a formalism for specifying revisions in knowledge bases and belief sets. This formalism extends logic programming with stable model semantics. Main objects of our system are revision programs consisting of revision rules. A revision rule expresses a specification of change or a constraint on a knowledge base. There are two types of revision rules. In-rules require that an element be in a knowledge base whenever some other elements are in the knowledge base and yet other elements are absent from it. Similar conditions in an out-rule force the absence of an element from the knowledge base.