Exploiting Conjunctive Queries in Description Logic Programs

We present cq-programs, which enhance nonmonotonic description logics (dl-) programs by conjunctive queries (CQ) and union of conjunctive queries (UCQ) over Description Logics knowledge bases, as well as disjunctive rules. dlprograms had been proposed as a powerful formalism for integrating nonmonotonic logic programming and DL-engines on a clear semantic basis. The new cq-programs have two advantages. First, they offer increased expressivity by allowing general (U)CQs in the body. And second, this combination of rules and ontologies gives rise to strategies for optimizing calls to the DL-reasoner, by exploiting (U)CQ facilities of the DL-reasoner. To this end, we discuss some equivalences which can be exploited for program rewriting and present respective algorithms. Experimental results for a cq-program prototype show that this can lead to significant performance improvements.

• Type: Conference
• Year: 2007
• Where: DLOG
• Authors: Thomas Eiter, Giovambattista Ianni, Thomas Krennwallner, Roman Schindlauer
• Keywords: Automated Reasoning, Conjunctive Queries, Description Logics, DLOG 2007, Nonmonotonic Description Logics