- From: Patrick Stickler <patrick.stickler@nokia.com>
- Date: Sat, 16 Feb 2002 18:15:44 +0200
- To: Pat Hayes <phayes@ai.uwf.edu>, Dan Connolly <connolly@w3.org>
- CC: RDF Core <w3c-rdfcore-wg@w3.org>
On 2002-02-15 23:39, "ext Pat Hayes" <phayes@ai.uwf.edu> wrote: >> On Thu, 2002-02-14 at 22:58, Pat Hayes wrote: >>> Latest version of the datatype summary document now available at >>> >>> http://www.coginst.uwf.edu/users/phayes/DatatypeSummary3.html >> >> Where's S-B? >> >> i.e. what name are we giving to the class >> of lexical representations of dates, so we can >> use them in range constraints, ala... >> >> dc:date rdfs:range rdfdt:date.lex. >> >> _:work dc:date "2002-02-14". > > As discussed, that would be the rdf:range of a datatype property. > I'll add comments about this in a version 4 tonight. I don't think so. My understanding about rdfs:range and general RDF classes is that, a non-datatype class is simply a value space. It's a set of values. And rdfs:range is a constraint on a property to have property values (statement objects) that are members of the value space (the only space) of the specified class. A datatype class (rdfs:Datatype) is a special kind of class which, in addition to having the value space, the members of that value space have lexical representations, defined by an additional lexical space, and there is an N:1 mapping from the lexical space to the value space. Thus, an rdfs:range constraint on a datatype class is no different than an rdfs:range constraint on a non-datatype class, it simply constrains to the value space of the class, whether it is datatype class is not relevant. Thus dc:date rdfs:range xsd:date simply constrains the property values of the dc:date property to be members of the value space of xsd:date, irrespective of their lexical representations. Now, rdfs:drange constrains both to the value space, and requires that the value itself is represented by a member of the lexical space of that datatype class. Thus, to say dc:date rdfs:drange xsd:date means that, in addition to constraining the property values of the dc:date property to members of the value space of xsd:date, they must also have lexical representations that are members of the lexical space of xsd:date and there must be a valid mapping between the lexical representation and the value. Per my recent proposal that the semantics of rdfs:drange denote a union of the value space and lexical space of the datatype class, one can use either the inline or value triple idioms and achieve the desired interpretation. But rdfs:range says nothing whatsoever about lexical spaces. Eh? Cheers, 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 Saturday, 16 February 2002 11:14:19 UTC