- From: Jan Grant <Jan.Grant@bristol.ac.uk>
- Date: Fri, 29 Sep 2000 15:10:32 +0100 (BST)
- To: Graham Klyne <GK@Dial.pipex.com>
- cc: Jan Grant <Jan.Grant@bristol.ac.uk>, rdf interest <www-rdf-interest@w3.org>
On Fri, 29 Sep 2000, Graham Klyne wrote: > At 10:21 AM 9/29/00 +0100, Jan Grant wrote: > >and loosely: > > > >P has a range of (a member of the union of A and B) > > > > A --[rdfs:subclassOf]-> anon:C > > B --[rdfs:subclassOf]-> anon:C > > P --[rdfs:range]-> anon:C > > > >(give anon:C a real URI if you prefer). > > > >Are there problems with this scheme? > > I like the approach. > > > I don't know if it's a _problem_, but I don't think this actually allows > one to validate OR infer much in an open-world environment. E.g. the above > statements don't allow us to infer from: > S --P--> O > the truth or falsity of any of the following: > O --rdf:type--> A > O --rdf:type--> B > O --rdf:type--> D > > > Similarly, they don't allow us to validate a statement like: > S --P--> O > where > O --rdf:type--> D > > > I guess what it does tell us is that > S --P--> O > where > O --rdf:type--> A > or > O --rdf:type--> B > is definitely valid. Yep. By 'validation' I meant the last case. I get the feeling that everyone agrees that the disjuntive semantics is "weaker": at least, in the standard picture of RDF usage where the closed-world assumption doesn't hold. Being able to model disjunctive semantics like this, however, should suffice for those people who need it. _Application_ level uses of RDF will obviously involve attaching additional semantics (the "F" stands for "Framework", remember) which might well allow stronger interpretations of the disjuntive case. -- jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/ Tel +44(0)117 9287163 Fax +44 (0)117 9287112 RFC822 jan.grant@bris.ac.uk ioctl(2): probably the coolest Unix system call in the world
Received on Friday, 29 September 2000 10:11:27 UTC