- From: Ian Horrocks <horrocks@cs.man.ac.uk>
- Date: Fri, 3 Oct 2003 12:09:41 +0100
- To: pat hayes <phayes@ihmc.us>
- Cc: www-webont-wg@w3.org, Jeff Pan <panz@cs.man.ac.uk>
This looks fine to me. Ian On October 2, pat hayes writes: > > >Dear All, > > > >Jeff and I (mostly Jeff) have looked at the latest RDF MT, in > >particular the Datatypes section. We did not have time for an > >exhaustive review, but here are some comments: > > > >Regards, Ian > >======================================== > > Further to my last message, here is a proposed text for the relevant > part of section 7. This effectively defines 'datatype clash' more > broadly to cover all the various cases, including the ill-formed > literal cases. > > ---------------------- > > If the datatypes in the datatype map D impose disjointness conditions > on their value spaces, it is possible for an RDF graph to have no > D-interpretation which satisfies it. For example, XML Schema defines > the value spaces of xsd:string and xsd:decimal to be disjoint, so it > is impossible to construct a XSD-interpretation satisfying the graph > > <ex:a> <ex:b> "25"^^xsd:decimal . > <ex:b> rdfs:range xsd:string . > > This situation could be characterized by saying that the graph is > XSD-inconsistent, or more generally as a datatype clash. Note that it > is possible to construct a satisfying rdfs-interpretation for this > graph, but it would violate the XSD conditions, since the class > extensions of I(xsd:decimal) and I(xsd:string) would have a nonempty > intersection. > > Datatype clashes can arise in several other ways. For example, any > assertion that something is in both of two disjoint dataype classes: > > _:x rdf:type xsd:string . > _:x rdf:type xsd:decimal . > > or that a property with an 'impossible' range has a value: > > <ex:p> rdfs:range xsd:string . > <ex:p> rdfs:range xsd:decimal . > _:x <ex:p> _:y . > > would constitute a datatype clash. A datatype clash may also arise > from the use of a particular lexical form, for example: > > <ex:a> <ex:p> "2.5"^^xsd:decimal . > <ex:p> rdfs:range xsd:integer . > > or by the use of an ill-typed lexical form: > > <ex:a> <ex:p> "abc"^^xsd:integer . > <ex:p> rdfs:range xsd:integer . > > Datatype clashes are the only inconsistencies recognized by this > model theory ; note however that datatype clashes involving XML > literals can arise in RDF and RDFS. > > ----------- > -- > --------------------------------------------------------------------- > IHMC (850)434 8903 or (650)494 3973 home > 40 South Alcaniz St. (850)202 4416 office > Pensacola (850)202 4440 fax > FL 32501 (850)291 0667 cell > phayes@ihmc.us http://www.ihmc.us/users/phayes >
Received on Friday, 3 October 2003 07:11:18 UTC