Rewriting-based instance retrieval for negated concepts in description logic ontologies

Abstract

Instance retrieval computes all instances of a given concept in a consistent description logic (DL) ontology. Although it is a popular task for ontology reasoning, there is no scalable method for instance retrieval for negated concepts by now. This paper studies a new approach to instance retrieval for negated concepts based on query rewriting. A class of DL ontologies called the inconsistency-based first-order rewritable (IFO-rewritable) class is identified. This class guarantees that instance retrieval for an atomic negation can be reduced to answering a disjunction of conjunctive queries (CQs) over the ABox. The IFOrewritable class is more expressive than the first-order rewritable class which guarantees that answering a CQ is reducible to answering a disjunction of CQs over the ABox regardless of the TBox. Two sufficient conditions are proposed to detect IFO-rewritable ontologies that are not first-order rewritable. A rewriting-based method for retrieving instances of a negated concept is proposed for IFO-rewritable ontologies. Preliminary experimental results on retrieving instances of all atomic negations show that this method is significantly more efficient than existing methods implemented in state-of-the-art DL systems.