Next step for NoHR: OWL 2 QL

Abstract

The Protégé plug-in NoHR allows the user to combine an OWL 2 EL ontology with a set of non-monotonic (logic programming) rules – suitable, e.g., to express defaults and exceptions – and query the combined knowledge base (KB). The formal approach realized in NoHR is polynomial (w.r.t. data complexity) and it has been shown that even very large health care ontologies, such as SNOMED CT, can be handled. As each of the tractable OWL profiles is motivated by different application cases, extending the tool to the other profiles is of particular interest, also because these preserve the polynomial data complexity of the combined formalism. Yet, a straightforward adaptation of the existing approach to OWL 2 QL turns out to not be viable. In this paper, we provide the non-trivial solution for the extension of NoHR to OWL 2 QL by directly translating the ontology into rules without any prior classification. We have implemented our approach and our evaluation shows encouraging results.