Disjunctive Logic Programs with Inheritance

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.