Updates with Disjunctive Information: From Syntactical and Semantical Perspectives

Abstract

The possible models approach is a classical minimal change semantics for knowledge base update, which provides an exclusive interpretation for disjunctive information in updates. It has been recognized that the exclusive interpretation for disjunction may be problematic under some circumstances. In this paper, we investigate inclusive interpretations for disjunctions in updates from both syntactical and semantical viewpoints. In particular, we propose two approaches for disjunctive update—the minimal change with exceptions (MCE) and the minimal change with maximal disjunctive inclusions (MCD). Both approaches provide inclusive interpretations for disjunctions in updates, though the first is syntax-based and the second is model-theoretic. We then characterize the MCE and MCD in terms of alternative minimal change criteria and relate them to traditional Katsuno and Mendelzon's update postulates.