- From: Patrick Stickler <patrick.stickler@nokia.com>
- Date: Mon, 11 Mar 2002 17:08:21 +0200
- To: "ext jos.deroo.jd@belgium.agfa.com" <jos.deroo.jd@belgium.agfa.com>
- CC: RDF Core <w3c-rdfcore-wg@w3.org>
On 2002-03-11 1:31, "ext jos.deroo.jd@belgium.agfa.com" <jos.deroo.jd@belgium.agfa.com> wrote: > >> Here's my very short list of outstanding issues that I see as >> still remaining to be resolved for the stake-in-the-ground datatyping >> proposal, with proposed resolutions: >> >> >> 1. Union versus non-union interpretation of datatypes >> >> Overview of Issue: >> >> a) XML Schema associates a single URI with a datatype. That >> URI denotes the entire datatype, not just its value space. >> Stating that the URI only denotes the value space may be >> considered contrary to the XML Schema usage and leaves >> datatypes without a formally defined URI denoting the entire >> datatype. > > Per ?d rdfs:domain ?d that single uri denotes the valuespace and > the valuespace-to-lexicalspace mapping but *not* the lexicalspace. This is what the latest dt proposal asserts, but this is exactly what I'm challenging. That '?d rdfs:domain ?d' is incorrect, because a datatype URI denotes the entire datatype, not just the value space. Thus, taking the union interpretation of datatype URIs, a datatype URI can't be used to denote the domain of itself. What we rather need to say is: { ?d rdf:type rdfs:Datatype } log:implies { ?d hasValueSpace ?V ; rdfs:domain ?V } . and the value space remains unnamed. C.f. The complete set of implications of rdfs:Datatype class membership would be something like: { ?d rdf:type rdfs:Datatype . } log:implies { ?d rdfs:hasValueSpace ?V . ?V rdf:type rdfs:DatatypeValueSpace . ?V rdfs:subClassOf ?d . ?V rdfs:subClassOf rdfs:DatatypeValue . ?d rdfs:hasLexicalSpace ?L . ?L rdf:type rdfs:DatatypeLexicalSpace . ?L rdfs:subClassOf ?d . ?L rdfs:subClassOf rdfs:DatatypeLiteral . ?d rdf:type rdfs:Property . ?d rdfs:domain ?V . ?d rdfs:range ?L . } . I didn't consider the extra vocabulary in my examples as essential, but perhaps it would be useful to provide such an example in a non-normative section to clarify the nature of datatype classes. ??? > Maybe for S-B we could use ``?p rdfs:range [ xsi:type ?d ]'' > to say that the range of ?p is the lexical space of the datatype ?d > e.g. > eg:Jenny eg:age "35" . > > eg:age rdfs:range _:1 . > _:1 xsi:type xsd:number . Perhaps. I wish, though, that we could find a way to express such constraints using neutral RDF/S vocabulary, if possible. And actually, I wonder if folks ever really will need to constrain graphs to only one or the other idiom. Devising a means to constrain property values to only the inline or only the datatype triple idiom might best be left for later, if and when it is determined to be a real need. Patrick -- Patrick Stickler Phone: +358 50 483 9453 Senior Research Scientist Fax: +358 7180 35409 Nokia Research Center Email: patrick.stickler@nokia.com
Received on Monday, 11 March 2002 10:06:28 UTC