Recovery of (Non)Monotonic Theories

We present a framework for recovery of nonmonotonic theories, i.e. of theories that are interpreted using a nonmonotonic semantics. Recovery of a nonmonotonic theory is needed if it does not have a model under the given nonmonotonic semantics, i.e. if the theory is non-monotonically inconsistent. With classical theories, inconsistency can only be removed by contracting the current theory; for nonmonotonic databases, however, it is in general unclear how to restore the consistency of a theory: indeed, several options for recovery that use (mixtures of) contractions and expansions have been proposed in the literature. In this paper, we propose a more fundamental approach to study the recovery problem by stating some rationality postulates for recovery. In these postulates we assume that, when recovering a theory T with respect to some intended semantics, one can fall back on a weaker, so called back-up semantics for T. Based on these rationality postulates, our general conclusion is tha...

• Type: Journal
• Year: 1998
• Where: AI
• Authors: Cees Witteveen, Wiebe van der Hoek
• Keywords: AI 1998, Artificial Intelligence, Nonmonotonic Semantics, Nonmonotonic Theories, Theory