- From: Patrick Stickler <patrick.stickler@nokia.com>
- Date: Fri, 08 Mar 2002 21:00:12 +0200
- To: RDF Core <w3c-rdfcore-wg@w3.org>
OK, folks, I'm deciding still to stand my ground on this one... ;-) At the f2f, I bowed to pressure to surrender my view that literals are not resources, figuring that perhaps I was not aware of some deicsions or general enlightenment of the WG since publication of RDFS 1.0. Though, in re-re-reading the RDFS rec, it remains clear to me, at least insofar as the original language is concerned, that members of the class rdfs:Literal are not members of the class rdfs:Resource. The key criteria for being a member of rdfs:Resource appears to be the ability to occur as the subject of a statement. Since literals cannot be subjects, they cannot be members of rdfs:Resource. Right? If that has changed, please tell me when, where and why. That's not to say that literals are not things in the universe, only that literals are not members of the RDF class rdfs:Resource. -- If that hasn't changed, then... One very direct benefit of upholding this disjunction and keeping literal nodes outside of rdfs:Resource is that, in conjunction with my proposed union-interpretation of datatype classes, it provides a very nice and intuitive means of restricting property values to either the lexical space or value space of the datatype. E.g. :p rdfs:range xsd:integer . :p rdfs:range rdfs:Resource . restricts property values to datatype values (the datatype triple idiom) of xsd:integer, and :p rdfs:range xsd:integer . :p rdfs:range rdfs:Literal . restricts property values to lexical forms (the inline idiom) of xsd:integer. Thus, if folks really, really want to restrict usage to one or the other idiom, they have a clear and straightforward means to do so. And furthermore, one can more precisely define the nature of implied value and lexical space classes, and the fact that the range of a datatype property is its lexical space and its domain is its value space. E.g. { :d rdf:type rdfs:Datatype . } log:implies { :d rdfs:hasValueSpace :V . :V rdf:type rdfs:DatatypeValueSpace . :V rdfs:subClassOf :d . :V rdfs:subClassOf rdfs:Resource . :d rdfs:hasLexicalSpace :L . :L rdf:type rdfs:DatatypeLexicalSpace . :L rdfs:subClassOf :d . :L rdfs:subClassOf rdfs:Literal . :d rdfs:domain :V . :d rdfs:range :L . } . which captures the semantics of datatype classes quite nicely, I think. Eh? 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 Friday, 8 March 2002 13:58:19 UTC