>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/phayesReceived on Thursday, 2 October 2003 21:47:42 EDT
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