Description Logics for the Semantic Web

The vision of a Semantic Web has recently drawn considerable attention, both from academia and industry. Description Logics are often named as one of the tools that can support the Semantic Web and thus help to make this vision reality. In this paper, we sketch what Description Logics are and what they can do for the Semantic Web. Descriptions Logics are very useful for defining, integrating, and maintaining ontologies, which provide the Semantic Web with a common understanding of the basic semantic concepts used to annotate Web pages. We also argue that, without the last decade of basic research in this area, Description Logics could not play such an important rôle in this domain. The Semantic Web and Ontologies For many people, the World Wide Web has become an indispensable means of providing and searching for information. Searching the Web in its current form is, however, often an infuriating experience since today’s search engines usually provide a huge number of answers, many of which are completely irrelevant, whereas some of the more interesting answers are not found. One of the reasons for this unsatisfactory state of affairs is that existing Web resources are usually only human understandable: the mark-up (HTML) only provides rendering information for textual and graphical information intended for human consumption. The Semantic Web [2] aims for machine-understandable Web resources, whose information can then be shared and processed both by automated tools, such as search engines, and by human users. In the following we will refer to consumers of Web resources, whether automated tools or human users, as agents. This sharing of information between different agents requires semantic mark-up, i.e., an annotation of the Web page with information on its content that is understood by the agents searching the Web. To make sure that different agents have a common understanding of this semantic mark-up, one needs ontologies that establish a joint terminology between the agents. Basically, an ontology [5] is a collection of definitions of concepts and the shared understanding comes from the fact that all the agents interpret the concepts w.r.t. the same ontology.