A Protégé Plugin for Querying and Reasoning on Persistent OWL Ontologies

The OWL language [1] is being widely used to define ontologies in the Web. This language provides three increasingly expressive sublanguages, namely OWL Lite, OWL-DL and OWL Full. The OWL-DL XML based syntax together with its correspondence with Description Logics (DL) [2], make it a good candidate to be the standard language for defining ontologies used by Semantic Web applications. However, there are still relatively few tools that allow us to manipulate, store and query ontologies defined using this language. Furthermore, Semantic Web applications, such as biological tools, use large ontologies, that is, ontologies with a large number (millions) of instances. Description logic based tools allow us to manage OWL-DL ontologies, but not very large ontologies. The development of tools for storing and querying OWL ontologies is currently under investigation. In this paper we present a plugin for the Protégé [3] environment for reasoning and querying OWL-DL ontologies stored in a relational database. We define a relational schema for storing OWL ontologies and a query/reasoning language, which supports reasoning on both, ontology structure and ontology instances. However, the main feature of this plugin is that developers of OWL-DL reasoners can customize it in order to use their own database and their own query language by means of several configurations files.