In this paper we define the notion of a compatibility relation so as to have a common framework for three nonmonotonic reasoning systems: normal logic programming, extended logic programming, and a restricted form of default logic. We show some properties of the maximal cliques of the pair-wise compatibility graph givn by the relation between the rules of the various reasoning systems. Properties that these maximal cliques possess are presented. A procedure to compute stable models (resp. answer sets, extensions) by enumerating maximal cliques with intelligent pruning is sketched.
Robert E. Mercer, Vincent Risch