- From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
- Date: Mon, 29 Apr 2002 11:02:43 +0100
- To: Dan Brickley <danbri@w3.org>
- Cc: <w3c-rdfcore-wg@w3.org>
At 06:20 AM 4/26/02 -0400, Dan Brickley wrote: >Another worry re terminology is that we have two Semantic Web working >groups. One group calls RDF schemas 'schemas', the other calls them >'ontologies'. To date we've not really used the latter term in RDF Core >specs. I personally don't like it, but that's not important. What is >importnat is terminological consistency at least within the RDF-based >corner of W3C's work. I'm stumped as to what we do about that. People will >ask us (of some RDF/XML schema that uses WebOnt machinery) whether it is >an 'ontology' or a 'schema'. Maybe we don't need an answer, but it does >seem a bit odd to not know collectively (in WebOnt + RDF Core) what we >think we're talking about. Editorial suggestions / contribs on this >welcomed... Hmmm... I think we ought to be wary about conflating schemas and ontologies. They are, I think, related but different ideas. Let's see if I can say why... According to John Sowa ["Knowledge Representation", appendix B], an ontology is: """ a catalogue of the types of things that are assumed to exist in a domain of interest [[D]] from the perspective of a person who uses a language [[L]] for talking about [[D]]. """ By contrast, I'd say that a schema is a catalogue of terms in some language, together with descriptions of how they can or should be used. The first difference that appears to me is that - an ontology is focused on the domain of discourse (semantics), even if with reference to a particular language, where - a schema is focused on the language (syntax). Further, it seems to me that a schema describes a vocabulary, only some terms of which may relate to ontological categories. In summary, I think we should restrict our discussions to the term "schema", as used to describe the vocabulary of RDF. Other groups may have a proper desire or need to use the term "ontology" to talk or reason about categories in their domain of discourse, using RDF language and schema as a vehicle for expressing some of those ideas. #g -- [More...] John Sowa's Knowledge Representation Appendix B goes on to discuss languages like CGs and KIF as ontologically neutral, and then to discuss informal and formal ontologies, and in particular axiomatized ontologies. Against that background, I think that RDF schemas are language tools that is/will be used and augmented by DAML/OWL to describe axiomatized ontologies. I think that the when a schema is described as an ontology, it would be more correct to call it a description of an ontology. This seems to be one of those conveniences of expression that is all very well as long as the underlying distinctions are understood. ------------------- Graham Klyne <GK@NineByNine.org>
Received on Monday, 29 April 2002 07:00:28 UTC