- From: Pat Hayes <phayes@ai.uwf.edu>
- Date: Fri, 15 Feb 2002 03:41:45 -0500
- To: Frank van Harmelen <Frank.van.Harmelen@cs.vu.nl>
- Cc: webont <www-webont-wg@w3.org>
>"Peter F. Patel-Schneider" wrote: >> >> Unfortunately, RDFS has precisely the class that prevents layering, >> rdfs:Class. Modifying RDFS to a layered theory might help, but this would >> be a significant modification of RDFS, as much of the justification for >> RDFS is precisely that it has classes like rdfs:Class. > >I think your last sentence exactly points at the heart of at least >one of our problems with RDF: > >"much of the justification for RDFS is precisely that it has classes >like rdfs:Class." > >I wonder if that is really true. No, I think this is nonsense. If you delete the last two words I would agree with it. >Yes, it is important for RDFS that we can form classes of classes >(and this feature is actively), but it is really necessary that >rdfs:Class is an instance of >*itself*< (ie breaking the layered >theory?) I don't think it is centrally important. However it is kind of cute, and I don't think it in fact is a problem either semantically or syntactically. > >I would suggest that most (if not: all) of the usage of rdfs:Class >would still work within a layered theory. Quite likely >(This is certainly the case in our own tools and > >Question: would anyone care to confirm or deny that people do not rely on > rdfs:Class being member of itself > (in particular the RDF experts in this group) > Only to the extent that it answers what is otherwise a puzzling question, viz. what IS rdfs:Class a member of? (Do you want to suggest that RDF should have ramified types?) >Question: is it really true that this would be all that much of a >change to RDF? > Syntactically? (My guess is no) It would complicate the statement of the syntax, as far as I can see to no useful purpose. > Semantically? (more so, but the model theory is still up for grabs) It would have no effect on the model theory at all; the MT would be word-for-word identical. > >I would suggest that getting RDFS to accept a layered theory would >solve many of our problems with building OWL on top of RDFS. I don't think so. I think it is completely irrelevant to those problems. >Frank. > ---- Pat -- --------------------------------------------------------------------- IHMC (850)434 8903 home 40 South Alcaniz St. (850)202 4416 office Pensacola, FL 32501 (850)202 4440 fax phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes
Received on Friday, 15 February 2002 03:41:47 UTC