On the semantics of logic programs

Abstract

The paper is a general overview of our approach to the semantics of logic programs whose aim is finding notions of models which really capture the operational semantics, and are therefore useful for defining program equivalences and for semantics-based program analysis. The approach leads to the introduction of extended interpretations which are more expressive than Herbrand interpretations. The semantics in terms of extended interpretations can be obtained as a result of both an operational and a fixpoint construction. It can also be characterized from the model-theoretic viewpoint, by defining a set of extended models which contains standard Herbrand models. The original construction for positive programs is shown to be applicable to other classes of logic programs, such as constraint logic programs, open programs, concurrent constraint programs and general programs.