NoHR: Integrating XSB prolog with the OWL 2 profiles and beyond

Abstract

We present the latest, substantially improved, version of NoHR, a reasoner designed to answer queries over hybrid theories composed of an OWL ontology in Description Logics and a set of nonmonotonic rules in Logic Programming. Whereas the need to combine the distinctive features of these two knowledge representation and reasoning approaches stems from real world applications, their integration is nevertheless theoretically challenging due to their substantial semantical differences. NoHR has been developed as a plug-in for the widely used ontology editor Protégé - in fact, the first hybrid reasoner of its kind for Protégé, building on a combination of reasoners dedicated to OWL and rules - but it is also available as a library, allowing for its integration within other environments and applications. Compared to previous versions of NoHR, this is the first that supports all polynomial OWL profiles, and even beyond, allowing for its usage with real-world ontologies that do not fit within a single profile. In addition, NoHR has now an enhanced integration with its rule engine, which provides support for a vast number of standard built-in Prolog predicates that considerably extend its usability.