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RE: hasKey axioms allowed for the empty set of properties

From: Boris Motik <boris.motik@comlab.ox.ac.uk>
Date: Tue, 14 Jul 2009 09:37:12 +0200
To: "'Michael Schneider'" <schneid@fzi.de>, "'W3C OWL Working Group'" <public-owl-wg@w3.org>
Message-ID: <D4E306114B13463881ACFEB7D634727C@wolf>
Hello,

This seems to me actually an important bug fix: the semantics of key axioms
without any properties is indeed very strange. Thanks Michael for catching this!

Given that it is a small change and that it was unintended (i.e., a bug), I've
taken the liberty of changing the documents; here are the diffs:

Syntax:
http://www.w3.org/2007/OWL/wiki/index.php?title=Syntax&diff=24801&oldid=24783

RDF Mapping:
http://www.w3.org/2007/OWL/wiki/index.php?title=Mapping_to_RDF_Graphs&diff=24799
&oldid=24615

If anyone objects, however, we can always roll these changes back.

Regards,

	Boris

> -----Original Message-----
> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org] On
> Behalf Of Michael Schneider
> Sent: 04 July 2009 19:09
> To: W3C OWL Working Group
> Subject: hasKey axioms allowed for the empty set of properties
> 
> Hi!
> 
> In the reverse RDF-Mapping of owl:hasKey, there is no constraint on the size
> of the argument list. This means that a key axiom may be defined for the empty
> set of properties. Also, it looks to me that the empty set is allowed in the
> Structural Specification (Functional Syntax), either.
> 
> I don't think that empty key axioms are particularly useful, and I can see
> that they have peculiar semantic ramifications.
> 
> So I propose to require at least one property for key axioms in both the
> Structural Spec and the reverse RDF-Mapping.
> 
> Cheers,
> Michael
> 
> --
> Dipl.-Inform. Michael Schneider
> Research Scientist, Dept. Information Process Engineering (IPE)
> Tel  : +49-721-9654-726
> Fax  : +49-721-9654-727
> Email: michael.schneider@fzi.de
> WWW  : http://www.fzi.de/michael.schneider
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> =======================================================================
Received on Tuesday, 14 July 2009 07:38:58 GMT

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