Lifting Transformations

Abstract

Lifting is a well known technique in resolution theorem proving, logic programming, and term rewriting. In this paper we formulate lifting as an efficiency-motivated program transformation applicable to a wide variety of nondeterministic procedures. This formulation allows the immediate lifting of complex procedures, such as the Davis-Putnam algorithm, which are otherwise difficult to lift. We treat both classical lifting, which is based on unification, and various closely related program transformations which we also call lifting transformations. These nonclassical lifting transformations are closely related to constraint techniques in logic programming, resolution, and term rewriting.