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[vass-02] rdfcore issue 'property instances' was: FORTH COMMENTS ON RDF Schema: Last Call

From: Dan Brickley <danbri@w3.org>
Date: Wed, 18 Jun 2003 10:36:05 -0400
To: Vassilis Christophides <christop@ics.forth.gr>
Cc: www-rdf-comments@w3.org
Message-ID: <20030618143604.GF11302@tux.w3.org>

Vassilis,

Following your RDF Core Last Call comments on RDF Schema, 
http://lists.w3.org/Archives/Public/www-rdf-comments/2003JanMar/0561.html 
we have discussed the issue 'property instances' in the working group. At 
the May 2nd teleconference[1] we unanimously resolved not to accept a need 
for changes to the RDF design on the basis of the arguments you presented. 

Regarding Property instances as resources, we note:

 * the WG discussed this issue at various times in the context of reification
  and revisions/clarifications to RDF's formal model per the original 1999 spec.

 * the mission of RDF Core as a WG is explicitly a clarificatory one; we 
 are not designing a new RDF, but clarifying the existing one.

 * many RDF _implementations_ allow for property instances (statements) to be
  tagged, grouped, labelled etc.

 * there are proposals (eg. N3) which make such facilities explicit within a 
  Semantic Web data language.

 * the WG will note to the Semantic Web Coordination Group that Last Call 
 comments were received on this, and that any (currently hypothetical) 
 RDF 2 charter designs should take this into account.

 * we do not intent to change the RDF formal model. While acknowledging that 
 a variety of alternate designs might have also been deployable, we believe the 
 current design is workable and has been implemented successfully.

In our discussions we also came to the conclusion that the use of 
domain/range constraints on a super-property might be one way of achieving 
some of the functionality you seek. While this is not modelled explicitly as 
a class, it nevertheless provides a mechanism for generalising about a 
category of property types. For example, we could assert an rdfs:range of 
'BiologicalEntity' for the property 'biologicalParent', which would also 
constrain sub-properties of 'biologicalParent' such as 'mother', 'father'.

Please reply to this message as to whether this response is
satisfactory, copying www-rdf-comments@w3.org. 

Thanks again for your review comments,

Dan 


[1] http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2003May/0031.html
Received on Wednesday, 18 June 2003 10:36:08 GMT

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