Disjunctive logic programs with inheritance

Abstract

The paper proposes a new knowledge representation language, called DLP^<, which extends disjunctive logic programming (with strong negation) by inheritance. The addition of inheritance enhances the knowledge modeling features of the language providing a natural representation of default reasoning with exceptions. A declarative model-theoretic semantics of DLP^< is provided, which is shown to generalize the Answer Set Semantics of disjunctive logic programs. The knowledge modeling features of the language are illustrated by encoding classical nonmonotonic problems in DLP^<. The complexity of DLP^< is analyzed, proving that inheritance does not cause any computational overhead, as reasoning in DLP^< has exactly the same complexity as reasoning in disjunctive logic programming. This is confirmed by the existence of an efficient translation from DLP^< to plain disjunctive logic programming. Using this translation, an advanced KR system supporting the DLP^< language has been implemented on top of the DLV system and has subsequently been integrated into DLV.