Description logic systems with concrete domains Applications for the semantic web.pdf

Description Logic Systems with Concrete Domains: Applications for the Semantic Web Volker Haarslev? and Ralf Mo?ller? ?Concordia University, Montreal ?University of Applied Sciences, Wedel Abstract The Semantic Web initiative defines important challenges for knowledge rep- resentation and database systems. Recently, several standards for representation languages have been proposed (RDF, DAML+OIL, OWL). We briefly discuss the logical basis of these representation languages by referring to description logic (DL) inferences systems. By introducing the DL inference system Racer we demonstrate that practically usable query engines for Semantic Web repre- sentation languages are available. Then, we argue that current representation languages for the Semantic Web are not sufficient for simple and well-defined representation problems that naturally arise in the context of Semantic Web ap- plications. In particular, we mention different kinds of algebraic constraints over various domains such as the reals or the natural numbers. We report on practi- cal experiences with DL reasoning systems (e.g., Racer) already supporting these representation means and argue for extensions to DAML+OIL or OWL. 1 Introduction The Semantic Web initiative defines important challenges for knowledge representation and database systems. Recently, one of the main standards for the Semantic Web has been proposed: the Resource Description Format (RDF [15]). Since RDF is based on XML it shares its document-oriented view of grouping sets of declarations or statements. With RDF’s triple-oriented style of data modeling, it provides means for expressing graph-structured data over multiple documents (whereas XML can only express graph structures within a specific document). As a design decision, RDF can talk about everything. Hence, in principle, statements in documents can also be referred to as resources. In particular, conceptual domain models can be represented as RDF resources. Conceptual domain model