- From: Dan Connolly <connolly@w3.org>
- Date: 16 Jun 2003 22:43:18 -0500
- To: Dave Beckett <dave.beckett@bristol.ac.uk>
- Cc: public-webont-comments@w3.org
On Fri, 2003-05-09 at 13:33, Dave Beckett wrote: > OWL Web Ontology Language Semantics and Abstract Syntax > W3C Working Draft 31 March 2003 > > 4.1. Translation to RDF Graphs > http://www.w3.org/TR/2003/WD-owl-semantics-20030331/mapping.html#4.1 > > This transformation table gives the mapping from OWL's abstract > syntax to RDF triples which means that if you have an OWL ontology in > the abstract syntax you can write it in OWL's transfer syntax - RDF triples. > > It is however more difficult to see how to go from RDF triples to > OWL's abstract syntax. As a semantic web technology, OWL builds on > RDF triples (and RDF on XML for syntax, URIs etc.) and this form of > presentation makes it harder to see how to start with RDF and gain > from OWL vocabulary. Discussion of whether and how to specify mappings between OWL abstract syntax and RDF graph syntax is the subject of this issue: 5.26-OWL DL Sytntax http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.26-OWLDLSyntax The working group discussed various alternatives, but eventually decided, 27 March 2003, on the design in the last call document. Note the outstanding dissent: 5.26 OWL DL Syntax - Formal Objection From: Jeremy Carroll (jjc@hpl.hp.com) Date: Fri, Mar 28 2003 http://lists.w3.org/Archives/Public/www-webont-wg/2003Mar/0264.html While the points in your comment are well-made, they don't seem to provide new information which would justify reopening the issue. You may be interested in continued related work, meanwhile... > In detail: > > 1) This presentation may make it hard to see how to transfer OWL - > from the transfer syntax (RDF triples) to the OWL abstract syntax. > > Running the (non-deterministic!) mapping rules backwards seems the > only way and is up to each implementer to work out how to do that. > Giving this mapping explicitly would be beneficial. If it depends > on the OWL subset in use, this should also be described. All of > this should preferably have and be linked to test cases. You may be interested in some related work by individuals in the working group: Parsing OWL, Sean Bechhofer, University of Manchester, June 02 2003 http://wonderweb.semanticweb.org/owl/parsing.shtml While this doesn't provide an actual specification of the reverse mapping, it does "describe a basic strategy that could be used ... to construct an OWL ontology that corresponds to the triples represented in the RDF" > 2) It is not clear from this mapping what restrictions there are on > any existing RDF such that it would already be legal OWL DL or OWL > Lite (apart from trying it out with an OWL validator). > > If the path from RDF to anything but OWL Full is not clear, it > seems that it is unlikely that benefits of OWL DL or OWL Lite will > be wholly realised. In order to clarify the path from RDF to OWL DL, informative section is being added to the OWL Reference: Appendix E. Rules of Thumb for OWL DL ontologies http://www.daml.org/2002/06/webont/owl-ref-proposed#app-DLinRDF > 3) The optional and non-deterministic mappings to/from triples are a > bad idea that are likely to cause interoperability problems and > make the mappings harder. I urge you to consider removing such > non-determinism. Note that "non-deterministic" does not mean "not completely specified"; it just means "not 1-1"; i.e. one abstract syntax structure corresponds to a number of RDF graphs. For example, for the intersection of classes A, B, and C, it doesn't matter what order they appear in an RDF collection. Taken literally, your request is to specify that exactly one RDF graph is allowed for any OWL abstract syntax structure. Could you confirm that this is what you're suggesting? It seems unlikely. > I note that several of these are related to having owl:Class and > rdfs:Class, a separate issue. > > Thanks > > Dave Please let us know if you find this response satisfactory. -- Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Monday, 16 June 2003 23:42:57 UTC