Absorption for ABoxes

Abstract

We consider the instance checking problem over S ? I Q ( D ) $\mathcal {SHIQ}(\mathbf{D})$ knowledge bases, that is, the problem of determining if the class membership of a given object is logically implied by a knowledge base expressed in terms of the description logic (DL) dialect S ? I Q ( D ) $\mathcal {SHIQ}(\mathbf{D})$ . Such problems are inevitable in conjunctive query evaluation over such knowledge bases, or indeed for any knowledge bases that rely on an ability to capture disjunction and/or negation in an underlying DL. This includes the problem of evaluating basic graph patterns occurring in SPARQL queries over RDF graphs with the so-called OWL 2 direct semantics entailment regime, that is, where the RDF graph is an OWL 2 ontology. Our main result is a novel method for such problems that derives from an adaptation of binary absorption. We show that the method works particularly well for knowledge bases that have a very large collection of factual assertions about individual objects.