Abstract not found

We introduce a calculus of stratified resolution, in which special attention is paid to clauses that "define" relations. If such clauses are discovered in the initial set of clauses, they are treated using the rule of definition unfolding, i.e. the rule that replaces defined relations by their definitions. Stratified resolution comes with a powerful notion of redundancy: a clause to which definition unfolding has been applied can be removed from the search space. To prove the completeness of stratified resolution with redundancies, we use a novel combination of Bachmair and Ganzinger's model construction technique and a hierarchical construction of orderings and least fixpoints.

. Connection graph resolution (cg-resolution) was introduced by Kowalski as a means of restricting the search space of resolution. Several researchers expected unrestricted connection graph (cg) resolution to be strongly complete until Eisinger proved that it was not. In this paper, ordered resolution is shown to be a special case of cg-resolution, and that relationship is used to prove that ordered cg-resolution is strongly complete. On the other hand, ordered resolution provides little insight about completeness of rst order cg-resolution and little about the establishment of strong completeness from completeness. A rst order version of Eisinger's cyclic example is presented, illustrating the diculties with rst order cg resolution. But resolution with selection functions does yield a simple proof of strong cg-completeness for the unit-refutable class. 1