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Re: RDF statements 'about=' <URI-reference>?

From: Pierre-Antoine CHAMPIN <champin@bat710.univ-lyon1.fr>
Date: Fri, 23 Jun 2000 08:29:26 +0200
Message-ID: <395303C6.1EBA3C10@bat710.univ-lyon1.fr>
To: Graham Klyne <GK@dial.pipex.com>
CC: www-rdf-comments@w3.org, CC/PP WG list <w3c-ccpp-wg@w3.org>
Graham Klyne wrote:
> 
> Folks,
> 
> I've just noticed that the RDF M&S document section 2.2.1, production [4],
> allows an RDF statement to have a URI-reference in an 'about=' clause.  The
> text three paragraphs below talks about a 'subcomponent' of a resource in
> relation to fragment identifiers in 'about='.
> 
> I believe this could be in conflict with the formal model, which states
> that the subject of an RDF statement is a _resource_.
> 
>  From RFC 2396:
> 
>           The resource is the conceptual mapping to an entity or set of
>           entities,
> 
> a fragment identifier has meaning only in conjunction with some specific
> _entity_ associated with a resource (a MIME type is needed for it to be
> interpreted).  I'm not sure what a 'subcomponent' of a resource can be
> taken to mean.

as I understand it,
this is based on the assumption that most URIs refer to a unique entity,
so the resource and the entity can be considered equivalent.
I guess most will agree that this assumption is too strong.

Anyway, people are much more interested in entities
than in "resources" according to the definition above.
What I want to make clear is that, even without using fragment identifiers,
RDF description often refer to *one* of the entities mapped by the resource,
rather than the mapping itself.

Which brings us back to an idea you raised, Graham :
storing with each triple the context it was stated in.
To take back Dan Brickley's example, with the W3C logo :

 I use the syntax (Subject,Predicate,Object,Context) :

 (http://w3.org/logo , s1:imageType , s1:GIF , http://here.com/foo.rdf)
 (http://w3.org/logo , s1:imageType , s1:PNG , http;//there.fr/bar.rdf)

without contexts, those two statements would be contradictory,
though they are both right, in a sense.

with context, they is no more contradiction;
we can just infer that the two contexts do not share a common view of the logo,
and that it won't be safe to mix statement from both of them.

  Pierre-Antoine

NOTE1 :
the 4-uple model (subject, predicate, object, context) could be built *above* RDF,
by means of reification.

NOTE2 :
do you Graham are aware of SHOE's Claim model.
It works quite the same way.

--- Quid quid Latine dictum sit, altum viditur
    Whatever is said in Latin sounds important.
Received on Friday, 23 June 2000 02:29:10 GMT

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