The Ecology of Ontologies in the Public Domain

Abstract

Since the announcement of the creation of a Web Ontology Working Group in 2001, two standards, DAML+OIL[1] and its successor, the Web Ontology Language (OWL) [2] were introduced. The latter is now the agreed-upon standard for formally specifying knowledge in the web and its introduction has renewed the focus on ontologies. Categories of researchers interested in ontologies include philosophers, software developers, computational linguists, biologists and logicians, and their motives are varied. Much debate now focuses on the criteria by which ontologies should be evaluated [3] and this debate is often driven by the question regarding the usefulness of ontologies for applications such as support for natural language processing [4] text mining [5], annotation of genes for gene expression analysis [6], inference or knowledge discovery in general, the facilitation of data integration [7], providing cornerstones of the Semantic Web [8], and as educational resources [9] There is however general agreement that Ontologies can serve as portable and easily exploitable conceptualizations for use in a multitude of computational applications. This has lead to an increase in the creation of ontologies and the emergence of a new generation of computational ontologists. In order to characterize the proliferation of ontologies in the public domain we conducted a study to assess and review the general characteristics of existing OWL ontologies paying attention to features such as their abundance, continuing availability, originating sources and domain covered. Our long-term goal is to evaluate ontologies in light of their suitability for reasoning that yields non-obvious insight or new knowledge in the corresponding domain. The next section discusses criteria and related work for ontology evaluation. We then report on the findings from our survey of ontologies in the public domain and on their domain dependent and domain independent features. The paper concludes with a summary and an outlook on future research.