W3C home > Mailing lists > Public > www-rdf-comments@w3.org > January to March 2003

Re: abstract class

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Thu, 23 Jan 2003 19:51:17 +0000
Message-Id: <5.1.0.14.0.20030123193755.0a9f3730@localhost>
To: marc@jfcarrion.com, www-rdf-comments@w3.org

Hi Marc,

This message has been posted to the RDF comments mailing list and I note 
also the discussion on RDF interest beginning with:

   http://lists.w3.org/Archives/Public/www-rdf-interest/2003Jan/0140.html

I understand that what you would like to be able to do is to express the 
fact that given:

   sc1 rdfs:subClassOf c .
   sc2 rdfs:subClassOf c .
   c   rdf:type        rdfs:Abstract .

there are no instances of c that are not instances of either sc1 or sc2.

This is fraught with difficulties for a number of reasons:

   1. you want to express a negation.  that is beyond the expressive power 
of RDF, and would be a major change to introduce.

   2. you want to express a closed world assumption.  how do I know that 
there is not an sc3 that you just haven't told me about.

If you need this sort of expressive power, then you need a powerful 
language such as daml+oil or owl.

At 07:27 23/01/2003 -0800, Marc Carrion wrote:

[...]

> > >
> > >    PS: Just a thought. 'rdfs:seeAlso'
> > 'rdfs:domain'
> > >is 'rdf:Resource', the last resource defined in the
> > >new schema
> > >       <rdf:Description
> > >rdf:about="http://www.w3.org/2000/01/rdf-schema#">
> > >          <rdfs:seeAlso
> >
> >rdf:resource=http://www.w3.org/2000/01/rdf-schema-more#"/>
> > >       </rdf:Description>
> > >         http://www.w3.org/2000/01/rdf-schema# is
> > not
> > >a 'rdf:Resource',

On what basis do you say that?  To RDF, anything identified by an RDF URI 
Reference is a resource.

Brian
Received on Thursday, 23 January 2003 14:51:34 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Friday, 21 September 2012 14:16:31 GMT