Detecting Different Versions of Ontologies in Large Ontology Repositories

There exist a number of large repositories and search engines collecting ontologies from the web or directly from users. While mechanisms exist to help the authors of these ontologies manage their evolution locally, the links between different versions of the same ontology are often lost when the ontologies are collected by such systems. By inspecting a large collection of ontologies as part of the Watson search engine, we can see that this information is often encoded in the identifier of the ontologies, their URIs, using a variety of conventions and formats. We therefore devise an algorithm, the Ontology Version Detector, which implements a set of rules analyzing and comparing URIs of ontologies to discover versioning relations between ontologies. Through an experiment realized with 7000 ontologies, we show that such a simple and extensible approach actually provides large amounts of useful and relevant results. Indeed, the information derived from this algorithm helps us in understanding how version information is encoded in URIs and how ontologies evolve on the Web, ultimately supporting users in better exploiting the content of large ontology repositories.