Implementing the OWL Reasoner in the Virtual Knowledge Graph System Ontop

Abstract

Ontop is a well-known framework designed to facilitate ontology-based data access. It supports two major APIs: RDF4J API for query answering and the SPARQL endpoint, and OWL API for editing ontology and mapping in the Protégé plugin. Ontop internally supports reasoning with the OWL2 QL ontology language using a Directed Acyclic Graph (DAG)-based algorithm, but this reasoning capability is only available through the RDF4J API, but not in OWL API, which limits its ability to handle complex inference tasks in Protégé. To close this gap, in this paper, we propose an enhancement to Ontop by properly implementing the OWLReasoner interface in the OWL API. This is achieved by leveraging the internal DAG-based ontology representation. We have validated our implementation through extensive testing and demonstrated the improvements in the Protégé plugin user interface.