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Re: abstract class

From: Marc Carrion <marc_carrion@yahoo.es>
Date: Fri, 24 Jan 2003 01:27:20 -0800 (PST)
Message-ID: <20030124092720.57383.qmail@web11906.mail.yahoo.com>
To: Brian McBride <bwm@hplb.hpl.hp.com>, marc@jfcarrion.com, www-rdf-comments@w3.org


--- Brian McBride <bwm@hplb.hpl.hp.com> wrote:
> 
> At 14:16 23/01/2003 -0800, Marc Carrion wrote:
> 
> [...]
> 
> > >
> > > 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.
> >   More or less, I would like to say that I don't
> have
> >instances of c, that would be enough.
> 
> That would still be negation.  RDF cannot do that.
> 
> Think carefully about what you mean by "instance
> of".
> 
> In RDF, as has been pointed out on RDF interest, any
> instance of sc1 is an 
> instance of c.  So when you say you want to say
> there are no instances of 
> c, you would also be saying there are no instances
> of sc1 and no instances 
> of sc2.  I doubt that's what you mean.
> 
   Yes and No. Let me explain, and I beg your pardon
again for my english. I understand that any instance
of a class that is subclass of c is instance of c (The
same in UML, Java, C++, ...) but I cannot say in a RDF
instance that (x -rdf:type-> c) (the same in UML,
Java, C++, ...) I'm going to infer it from the
instance and the schema. Does it make sense? I'm not
trying to express a NOT I trying to make a diference
in the range  property of the Property rdf:type. Is it
more clear in this way?

> 
> >   If anything identified with a RDF URI it's a
> >Resource, why all the classes I define should
> extend
> >from resource?
> 
> I don't know what you mean by "extend from".
  Excuse me for my english again (Now that I read that
I don't know why I wrote it) I meant The classes you
define in the schema should be subclass of
rdf:Resource, at least all them are in the schema of
the RDFS.
 
> Brian
  Thanks again for your time,
                              Marc


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Received on Friday, 24 January 2003 04:27:25 GMT

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