A Decomposition-based Approach to Optimizing Conjunctive Query Answering in OWL DL

Abstract. Scalable query answering over Description Logic (DL) based ontolo-gies plays an important role for the success of the Semantic Web. Towards tack-ling the scalability problem, we propose a decomposition-based approach to op-timizing existing OWL DL reasoners in evaluating conjunctive queries in OWL DL ontologies. The main idea is to decompose a given OWL DL ontology into a set of target ontologies without duplicated ABox axioms so that the evaluation of a given conjunctive query can be separately performed in every target ontology by applying existing OWL DL reasoners. This approach guarantees sound and com-plete results for the category of conjunctive queries that the applied OWL DL reasoner correctly evaluates. Experimental results on large benchmark ontologies and benchmark queries show that the proposed approach can significantly im-prove scalability and efficiency in evaluating general conjunctive queries.