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Re: Missing AllSame

From: Guus Schreiber <schreiber@swi.psy.uva.nl>
Date: Thu, 19 Jun 2003 11:19:00 +0200
Message-ID: <3EF18004.6000204@swi.psy.uva.nl>
To: Ron Alford <ronwalf@wam.umd.edu>
CC: public-webont-comments@w3.org

Ron Alford wrote:

 > Hello,
 > Since there is an owl:AllDifferent, why is there not an owl:AllSame? 
  I have a need for it on my current project.  It would be nice for it 
to have similar semantics to owl:AllDifferent.
 > Thanks,
 >   - Ron Alford
 > --
 > Ron Alford, KB0NUV
 > http://volus.net/~ronwalf


Thanks for your comment.

We introduced a AllDifferent construct because of the exponential growth 
of the number of differentFrom statements; see Sec. 6.3 of OWL Reference [1]

For ontologies in which the unique-names assumption holds, the use of 
owl:differentFrom is likely to lead to a large number of statements, as 
all individuals have to be declared pairwise disjoint.

The case is different for sameAs, because sameAs only leads to linear 
growth of the number of statements. (due to the transitive nature of 
sameAs, the statements "a sameAs b" and "b sameAs c" already imply "a 
sameAs c").

Please respond, copying public-webont-comments@w3.org, as to whether
you are satisfied with this response.

Guus Schreiber

[1] http://www.w3.org/TR/owl-ref/#AllDifferent-def
Received on Thursday, 19 June 2003 05:19:01 UTC

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