Transforming normal logic programs to constraint logic programs

Abstract

A normal logic program P is transformed to another Pω by a bottom-up computation on the positive component of P while the negative counterpart is left untouched. The declarative semantics of P is given by the completion of Pω. The completed predicate definitions in Pω, if they do not contain local variables, can be used as a basis for expanding each negated atom in the bodies of Pω. We show that for a class of programs where every negative subgoal can be expanded, the resultant program P′ is a definite logic program with equality and disequality constraints. If the program falls outside this class, the resultant program may be executed using constructive negation. Our proposed scheme provide..