- From: Dan Connolly <connolly@w3.org>
- Date: 03 Jan 2002 10:58:08 -0600
- To: Frank van Harmelen <Frank.van.Harmelen@cs.vu.nl>
- Cc: www-webont-wg@w3.org
On Thu, 2002-01-03 at 09:46, Frank van Harmelen wrote: > > In various emails to the Working Group, and also in various off-line conversations, a number of people have become very worried about the layering of OWL on top of RDF and RDF Schema. > > The problems can be summarised as follows: > - RDF is not well suited as syntax carrier: > - the problems that Peter has identified with "additional" tuples > (which specify only syntax) ending up in the RDF model and breaking the inference Those "additional" tuples are a suggestion from PatH to RDF Core that the RDF Core WG has not yet decided on. I, for one, don't agree that they are/should-be part of RDF. > - problems with scoping scoping in RDF is quite simple, no? > - its inability to constrain the syntax adequately > (e.g., the problem with strange combinations of restrictions > which is responsible for much of the ugly DAML+OIL syntax). I'd rephrase this as: the awkwardness of dealing with n-ary (as opposed to binary) relationships. > - general unreadability by human processors > - RDF Schema has some unconventional features in its meta-model. > These were left out of DAML+OIL to keep the language simple, > well understood on formal grounds and non-controversial, > and now threaten to creep back in again. Which features? In what way were they left out of DAML+OIL? The axiomatic semantics of DAML+OIL specifies all of RDFS, no? I know the model-theoretic semantics for DAML+OIL doesn't cover all of RDFS, but that's a limitation of the mt-semantics, not a limitation of DAML+OIL, no? I think this is the heart of the matter, and I very much disagree that the layering of RDFS is a "mistake", as claimed in Metamodeling Architecture of Web Ontology Languages Jeff Pan, Ian Horrocks http://www.semanticweb.org/SWWS/program/full/paper11.pdf <- http://www.semanticweb.org/SWWS/program/index.html > Our conclusion is that these problems are much harder to solve than originally anticipated. > Therefore, we propose to take another route for specifying the syntax of OWL: > > 1. the syntax of class and property definitions in OWL (the ontology) is specified in XML I see this as a request to change our charter. I'm not convinced we should do this. > 2. this is done in such a way that RDF can be used to specify instances of the ontology > 3. we try to do 1. in such a way that significant parts of RDF Schema > end up as a sublanguage of OWL > > The advantage of using XML Note that we're already using XML by using RDF. > are both technical and (not unimportant) also political: > - XML is well suited for specifying syntax (in fact, that is its main goal in life) Please be more clear. Do you mean XML DTDs? or W3C XML Schema? > - it comes with a host of additional technology and standards that can then be exploited > for OWL (XLink, XPointer, XPath, XQuery, XSLT, etc) > (we can think of useful applications for all of these) I use those with RDF every day, since "RDF is an XML text format" -- http://www.w3.org/XML/1999/XML-in-10-points > - it will make our work immediately relevant to all of the XLM community. Our work is already immediately relevant to all of the XML community. cf RDF update: Query, XTM, Web Ontology and RDF Core 3 Sep 2001 | RDF | Edd Dumbill A round-up of recent developments in the RDF and Semantic Web world. W3C Web Ontology WG is open for business 15 Aug 2001 | W3C | Gabe Beged-Dov Dan Connolly announced that the W3C Web Ontology (WebOnt) WG is open in a message to the rdf-logic mailing list. -- http://www.xmlhack.com/search.php?q=webont&s=Search plus http://xml.coverpages.org/xmlAndSemanticWeb.html etc. > They share many of our goals, but there is a constant danger that they > will use different (XML-based) technology, instead of RDF based technology. RDF *is* an XML-based technology. > RDF is still being used for what its good at: specifying ground data-structures (the "Abox" of old). > > Whether 3 is achievable or not must be investigated. > If it is achievable, RDF Schema will not be a sublanguage of OWL, but parts of it will be. > > We suggest that this proposal is discussed at the face-to-face meeting. We will try to have a concrete proposal for (1) on the table before then. It will be helpful if we can get reactions on this proposal well before then (ie. now:-). > > Ian Horrocks, > Peter Patel-Schneider, > Frank van Harmelen. > ---- -- Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Thursday, 3 January 2002 11:58:04 UTC