In this paper, we have proposed both a syntax and a semantics of an ontology inference layer for the WWW based on XML and RDF schemas called OIL. One of our main motivations has been to try to ensure that such a proposed standard had a clear and well defined semantics--a common syntax is useless without an agreement as to what it all means.
The core we have currently defined can be justified from both a pragmatic and a theoretical point of view. From a pragmatic point of view, OIL covers consensual modeling primitives of Frame systems and Description Logics. From a theoretical point of view it appears quite natural to us to limit the expressiveness of this version so as to make subsumption decidable. This defines a well-understood subfragment of first-order logic. However, it is important to note that we are open for further discussions that may influence the final design of the language. Clearly future versions will provide variants with more expressive power which lack this reasoning support. Connecting OIL with Horn logic is probably the most challenging question and we will see how far we can get there.
We are currently evaluating the use of OIL in the two running IST projects, On-to-knowledge 1 and Ibrow 2 . In On-to-knowledge OIL will be extended to a full-fledged environment for knowledge management in large intranets. Unstructured and semi-structured data will be annotated automatically and agent-based user interface techniques and visualization tools will help user in navigate and query the information space. Here On-to-knowledge continues a line of research that was set up with SHOE (cf. [Luke et al., 1996] , [Heflin et al., 1999] ) and Ontobroker (cf. [Fensel et al., 1998] , [Fensel et al., 1999b] ): using ontologies to model and annotate the semantics of information in a machine processable manner.
1.
On-To-Knowledge: Content-driven Knowledge-Management Tools through Evolving Ontologies
started in January 2000. Project partners are the Vreije Universiteit Amsterdam (VU); the Institute AIFB, University of Karlsruhe, Germany; AIdministrator, the Netherlands; British Telecom Laboratories, UK; Swiss Life, Switzerland; CognIT, Norway; and Enersearch, Sweden.
http://www.ontoknowledge.org
2.
IBROW started with a pre-phase under the 4th European Framework and has become a full-fledged Information Society Technologies (IST) project under the 5th European Framework Program since February 2000. Results of its initial phase are described in
[Benjamins et al., 1999 (b)]
,
[Fensel & Benjamins, 1998]
, and
[Fensel et al., 1999a]
. Project partners are the University of Amsterdam; the Open University, UK; the Spanish Council of Scientific Research (IIIA) in Barcelona, Spain; the Institute AIFB, University of Karlsruhe, Germany: Stanford University, US: Intelligent Software Components S. A., Spain; and the Vrije Universiteit Amsterdam.
http://www.swi.psy.uva.nl/projects/ibrow/home.html