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RE: ISSUE: owl:Class name misleading; try owl:Set?

From: Dan Connolly <connolly@w3.org>
Date: 02 Jan 2003 18:44:56 -0600
To: Jim Hendler <hendler@cs.umd.edu>
Cc: Ziv Hellman <ziv@unicorn.com>, Jeff Heflin <heflin@cse.lehigh.edu>, "Peter F. "Patel-Schneider <pfps@research.bell-labs.com>, www-webont-wg@w3.org
Message-Id: <1041554696.19697.107.camel@dirk.dm93.org>

On Thu, 2003-01-02 at 17:12, Jim Hendler wrote:
> 3. We made a decision at that owl:class is a subclass of rdfs:class 
> but not identical to rdfs:class (per closing of issue 5.22 and the 
> "semantic consensus"). The RDF Schema document [1] reads:
> >RDF distinguishes between a class and the set of its instances. 
> >Associated with each class is a set, called the class extension of 
> >the class, which is the set of the instances of the class. Two 
> >classes may have the same set of instances but be different classes. 
> >For example, the tax office may define the class of people living at 
> >the same address as the editor of this document. The Post Office may 
> >define the class of people whose address has the same zip code as 
> >the address of the author. It is possible for these classes to have 
> >exactly the same instances, yet to have different properties. Only 
> >one of the classes has the property that it was defined by the tax 
> >office, and only the other has the property that it was defined by 
> >the Post Office.
> so if we decided to go with a purely set based approach, the we would 
> not be a subset,

No? Please explain.

As far as I can tell, it's quite coherent to say that
the class of sets is a subclass of the class of classes.
That's what cyc does

and KIF seems to do something similar... hmm...
taking another look, maybe this isn't relevant.

But still... please explain why it's not OK to say
that owl:Set rdfs:subClassOf rdfs:Class?

>  but a different animal, and  we would have to reopen 
> this discussion and issue (which I'm not inclined to do).

> My belief at the moment is that Semantics is consistent with the RDF 
> S use of class, and thus I'm reluctant to introduce a different 
> semantics at this late date.

I don't think I'm introducing a different semantics. I think
I'm just suggesting a more clear name for what we've got.

>   I believe it would require a strong 
> (STRONG) consensus of the WG if the decision is made to change this 
> (esp. as the current also  seems to be consistent with DAML+OIL 
> according to Peter in [2]).
> I may be misunderstanding the issue,

One of us is.

>  in which case I apologize, the 
> above are not meant to force a particular decision but to express 
> reluctance by the chair to introduce any major change on something 
> this basic.
> -JH
> [1] http://www.w3.org/2001/sw/RDFCore/Schema/200212bwm/
> [2] http://lists.w3.org/Archives/Public/www-webont-wg/2003Jan/0011.html
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Thursday, 2 January 2003 19:44:45 UTC

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