- From: Pat Hayes <phayes@ai.uwf.edu>
- Date: Fri, 5 Apr 2002 18:35:57 -0600
- To: Patrick Stickler <patrick.stickler@nokia.com>
- Cc: w3c-rdfcore-wg@w3.org
>On 2002-04-04 22:51, "ext Graham Klyne" <Graham.Klyne@MIMEsweeper.com> >wrote: > >> At 06:02 PM 4/4/02 +0100, Brian McBride wrote: >>> RDF Schema Issues >>> >>> * rdfs-constraining-containers: Should it be possible to constrain >>> the members of a container to be of a given type? >> >> I have a vague recollection we'd decided to defer this one?? (i.e. that >> RDFS 1.0 would provide no such capability.) > >I just recieved email from an implementor, Garret Wilson at Global Mentor, >that this is sorely needed for what they are doing. Then maybe they should be using DAML ? Look, RDF is a simple language. Various people will definitely want more than RDF can provide. We cannot insert new features just because they are needed: then we really would be doing Web Logic, as Massimo has accused us of doing. >I encouraged him to post a summary of the issue to RDF comments. > >My present take on this is that we need an additional constraint >property that applies to containers, such as rdfs:containerRange >which would be used in conjunction with rdfs:range. > >We can't simply extend the semantics of rdfs:range to collections >because one may wish to say that a property must take a collection, >not just a single value, and thus, rdfs:range breaks. What is >needed is an additional constraint mechanism, such as something >like rdfs:collectionRange which would apply to the members of >a collection. One would then specify e.g. that the property's >rdfs:range would be rdf:Bag and the rdfs:collectionRange would >be xsd:string, etc. We could add this, but its not clear what it would do to the semantics. I have an uneasy feeling that it might be quite complicated. This is a limited kind of a restriction-on-property (the container is restricted to things that have the appropriate range property) and that seems to rather go beyond RDFS. Pat -- --------------------------------------------------------------------- IHMC (850)434 8903 home 40 South Alcaniz St. (850)202 4416 office Pensacola, FL 32501 (850)202 4440 fax phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes
Received on Friday, 5 April 2002 19:40:00 UTC