On the Revision Of Conditional Belief Sets
Craig E. Boutilier, Moisés Goldszmidt · 1995
Abstract Both the dynamics of belief change and the process of reasoning by default can be captured with a conditional belief set, a set of ‘if-then’ rules held by a reasoning agent. In this paper we address the open problem of formalizing the revision of such a conditional belief set to incorporate new if-then rules, which may be interpreted as new default rules or new revision policies. We start by providing a purely semantic characterization, based on the semantics of conditional rules, which induces logical constraints on any such revision process. We then introduce logical (syntax-independent) and syntax-dependent techniques, and provide a precise characterization of the set of conditionals that hold after the revision. In addition to formalizing the dynamics of revising a default knowledge base, this work also provides some of the necessary formal tools for establishing the truth of nested conditionals and attacking the problem of learning new defaults.