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Re: owl:All(something) ??

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Mon, 12 May 2003 10:14:03 +0100
Message-ID: <16063.26075.6307.591354@merlin.horrocks.net>
To: Jim Hendler <hendler@cs.umd.edu>
Cc: webont <www-webont-wg@w3.org>

On May 11, Jim Hendler writes:
> 
> We have received a couple of comments that we should have some other 
> constructs similar to allDifferent
>   one comment suggest AllSame
> another asks for AllDisjoint
> 
> we need an answer as to why we included the first and not the latter 
> two, or we need to decide our current mechanism could be extended to 
> allow it to be used on other properties  (which would probably not 
> require another LC if we make it clear this is just a piece of 
> syntactic sugar since we have the appropriate semantics already).

As Jeremy points out, the various "same" relations are transitive, so
there is no n^2 blowup in the number of property relationships
required to express them, and the result is more compact than a (fully
expanded) list would be.

I also agree with Jeremy's account of the WG's thinking
w.r.t. disjoint classes - that it is much less frequently required,
and that the numbers (of classes) involved would typically be small
(compared to unique individuals). It was therefore decided that
additional syntax was not justified.

W.r.t. disjoint properties, I'm not sure we even considered it. It is
rarely asked for, and unlike the class/individual cases it is
relatively difficult to express in the existing language given
that we don't have property negation.

Ian





> 
> Any thoughts?
> 
> 
> 
> 
> -- 
> Professor James Hendler				  hendler@cs.umd.edu
> Director, Semantic Web and Agent Technologies	  301-405-2696
> Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
> Univ of Maryland, College Park, MD 20742	  240-731-3822 (Cell)
> http://www.cs.umd.edu/users/hendler
Received on Monday, 12 May 2003 05:14:17 GMT

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