W3C home > Mailing lists > Public > www-webont-wg@w3.org > July 2003

Re: TEST: 6 of 7: empty universe example,

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 23 Jul 2003 13:53:33 -0400 (EDT)
Message-Id: <20030723.135333.38029159.pfps@research.bell-labs.com>
To: jjc@hpl.hp.com
Cc: www-webont-wg@w3.org

From: Jeremy Carroll <jjc@hpl.hp.com>
Subject: TEST: 6 of 7: empty universe example, 
Date: Wed, 23 Jul 2003 19:20:15 +0300

> 
> Peter?
> (for book-keeping)
> 
> I had some outstanding actions on this one.
> 
> At one point it seemed that I would need to make owl:Thing finite but 
> non-empty to get different behaviour in DL and Full; it now appears that 
> owl:Thing can be empty in DL, os I have reduced the test to
> 
> owl:Thing owl:equivalentClass owl:Nothing
> 
> http://www.w3.org/2002/03owlt/editors-draft/draft/proposedByFunction#Thing-001
> http://www.w3.org/2002/03owlt/editors-draft/draft/proposedByFunction#Thing-002
> 
> this test is slightly different from the one that I was actioned to produce.
> 
> Jeremy

Hmm.  There may have been a slight glitch here at some time.

Right now, neither the direct semantics nor the rdfs semantics require that
the OWL DL universe of discourse is non-empty.

As Pat pointed out empty universes can cause problems in languages with
quantification.  I don't think that these problems surface in OWL.

peter
 
Received on Wednesday, 23 July 2003 13:53:43 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:58:01 GMT