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Semantics of rdf:Statement

From: Rinke Hoekstra <hoekstra@uva.nl>
Date: Fri, 20 Jul 2007 12:36:49 +0200
Message-ID: <46A09041.8060605@uva.nl>
To: semantic-web@w3.org
CC: Alexander Boer <aboer@uva.nl>, Thomas Gordon <thomas.gordon@fokus.fraunhofer.de>
Hi all,

I have a question regarding the rdf:Statement mechanism for reification: 
what is the semantics of an rdf:Statement consisting of multiple 
subject, predicate and object properties?

As far as we can tell, the RDF spec. is silent on this issue, and leaves 
implicit whether there is a 1:1 mapping between a triple and its 
reification as a rdf:Statement.

Supposing this 1:1 mapping holds, the following RDF should be incorrect, 
or at least problematic:

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
     <rdf:Statement rdf:ID="S1">
       <rdf:subject 
rdf:resource="http://www.leibnizcenter.org/information/people/rinke-hoekstra" 
/>
       <rdf:subject 
rdf:resource="http://www.leibnizcenter.org/information/people/alexander-boer" 
/>
       <rdf:predicate rdf:resource="http://description.org/schema/Creator"/>
       <rdf:predicate rdf:resource="http://description.org/schema/Fish"/>
       <rdf:object rdf:datatype=
          "http://www.w3.org/2001/XMLSchema#string">Rinke Hoekstra
       </rdf:object>
       <rdf:object rdf:datatype=
          "http://www.w3.org/2001/XMLSchema#string">Alexander Boer
       </rdf:object>
     </rdf:Statement>
</rdf:RDF>

The above example implicitly states that 
http://www.leibnizcenter.org/information/people/rinke-hoekstra and 
http://www.leibnizcenter.org/information/people/alexander-boer, and 
http://description.org/schema/Creator and 
http://description.org/schema/Fish pairwise point to the same resource. 
This is fine.

However, for datatype resources this is really problematic as the above 
RDF states that the *strings* "Rinke Hoekstra" and "Alexander Boer" are 
equal. Something which is clearly not true...

The W3C RDF Validator validates the above RDF as being correct. Is this 
intended?

Thanks,

	Rinke Hoekstra

-- 
----------------------------------------------
Drs. Rinke Hoekstra

Email: hoekstra@uva.nl   Skype:  rinkehoekstra
Phone: +31-20-5253499    Fax:   +31-20-5253495
Web:   http://www.leibnizcenter.nl/users/rinke

Leibniz Center for Law,         Faculty of Law
University of Amsterdam,           PO Box 1030
1000 BA  Amsterdam,            The Netherlands
----------------------------------------------

Received on Friday, 20 July 2007 10:37:14 UTC

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