Extending NoHR for OWL 2 QL∗

The Protége ́ plug-in NoHR allows the user to com-bine 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 ap-plication cases, extending the tool to the other pro-files is of particular interest, also because these pre-serve the polynomial data complexity of the com-bined 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 pre-processing or classification. We have implemented our approach and our evalu-ation shows encouraging results.