COHERENCE APPROACH TO LOGIC PROGRAM REVISION

In this paper, we present a new approach to the problem of revising ex tended programs; we base this approach on the coherence theory initial ly advocated by Gardenfors for belief revision. Our approach resolves contradiction by removing only conflicting information, not the believ ed source of it, and therefore, keeps information loss minimal. Furthe rmore, since there is no need to search for problematic assumptions, a s is done in the traditional assumption-removal approach, our approach provides a skeptical revision semantics that is tractable. We define the skeptical and credulous coherence semantics and show that both sem antics can be characterized in terms of the fixpoint semantics of a re vised program using a simple program-revision technique. These semanti cs provide a suitable framework for knowledge and belief revision in t he context of logic programs. Semantical properties and advantages of the proposed revision semantics are also analyzed.