An abductive framework for general logic programs and other nonmonotonic systems

We present an abductive semantics for general propositional logic programs which defines the meaning of a logic program in terms of its extensions. This approach extends the stable model semantics for normal logic programs in a natural way. The new semantics is equivalent to stable semantics for a logic program P whenever P is normal and has a stable model. The abductive semantics can also be applied to generalize default logic and autoepistemic logic in a like manner. Our approach is based on an idea recently proposed by Konolige for causal reasoning. Instead of maximizing the set of hypotheses alone we maximize the union of the hypotheses, along with possible hypotheses that are excused or refuted by the theory. 1