Proving termination of general Prolog programs

Abstract

We study here termination of general logic programs with the Prolog selection rule. To this end we extend the approach of Apt and Pedreschi [AP90] and consider the class of left terminating general programs. These are general logic programs that terminate with the Prolog selection rule for all ground goals. We introduce the notion of an acceptable program and prove that acceptable programs are left terminating. This provides us with a practical method of proving termination.The converse implication does not hold but we show that under the assumption of non-floundering from ground goals every left terminating program is acceptable. Finally, we prove that various ways of defining semantics coincide for acceptable programs. The method is illustrated by giving simple proofs of termination of a “game” program and the transitive closure program for the desired class of goals.KeywordsLogic ProgramLogic ProgrammingLevel MappingGround AtomGround InstanceThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.