NoHR (Nova Hybrid Reasoner) is a plug-in for the ontology editor Protégé that allows its users to query knowledge bases composed of both an Ontology in any of the tractable OWL 2 profiles (and even beyond) and a set of Reasoning Rules. Find out more here.

Using a top-down reasoning approach, which means that only the part of the ontology and rules that is relevant for the query is actually evaluated, NoHR combines the capabilities of ELK (for OWL 2 EL) and a dedicated direct translation for OWL QL and OWL 2 RL, respectively, but also Konclude and HermiT (for the combination of the features of these profiles), respectively, with the rule engine XSB Prolog to deliver very fast interactive response times.

NoHR is the first hybrid reasoner of its kind for Protégé.

New: Version 3.0 of NoHR is available, which now supports all polynomial OWL profiles (and even beyond) with an enhanced integration with its rule engine, which provides support for a vast number of standard built-in Prolog predicates. Follow this link to download NoHR 3.0.

NoHR is described in the following papers:

C. Lopes, M. Knorr and J. Leite, Integrating XSB prolog with the OWL 2 profiles and beyond, In M. Balduccini and T. Janhunen (Eds.), Logic Programming and Nonmonotonic Reasoning, 14th International Conference, LPNMR 2017, LNAI 10377, pp 236--249, Springer, 2017.

N. Costa, M. Knorr and J. Leite, Next Step for NoHR: OWL 2 QL, In M. Arenas, O. Corcho et al. (Eds) Proceedings of the 14th International Semantic Web Conference (ISWC'15), LNCS 9366, Springer-Verlag, 2015.

V. Ivanov, M. Knorr and J. Leite, A Query Tool for EL with Non-monotonic rules, In H. Alani, L. Kagal et al. (Eds.) Proceedings of the 12th International Semantic Web Conference (ISWC’13), LNCS 8218, pp 216-231, Springer-Verlag, 2013.