Digital Libraries and Web-based Information Systems

It has long been realised that the web could benefit from having its content understandable and available in a machine processable form, and it is widely agreed that ontologies will play a key role in providing much enabling infrastructure to support this goal. In this chapter we review briefly a selected history of description logics in web-based information systems, and the more recent developments related to OIL, DAML+OIL and the semantic web. OIL and DAML+OIL are ontology languages specifically designed for use on the web; they exploit existing web standards (XML, RDF and RDFS), adding the formal rigor of a description logic and the ontological primitives of object oriented and frame based systems. 14.1 Background and history The research world as well as the general public are unified in their agreement that the web would benefit from some structure and explicit semantics for at least some of its content. Numerous companies exist today whose entire business model is based on providing some semblance of structure and conceptual search (i.e., yellow pages and search). To paraphrase Milne [1928], “Providing structure is one of the things description logics do best!”. In this chapter we review briefly the history of description logics in web-based information systems, and the more recent developments related to OIL (the Ontology Inference Layer), DAML (the DARPA Agent Markup Language), DAML+OIL and the “semantic web.” The web has been a compelling place for research activity in the last few years, and as we can not cover all the many efforts we will choose a few exemplar efforts that illustrate some of the key issues related to description logics on the web.