Next Step for NoHR: OWL 2 QL

Abstract. The Protége ́ 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 complex-ity) 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 moti-vated 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 ap-proach 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 translat-ing the ontology into rules without any prior classification. We have implemented our approach and our evaluation shows encouraging results.