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Re: What is an RDF Query?

From: pat hayes <phayes@ai.uwf.edu>
Date: Tue, 11 Sep 2001 13:41:02 -0500
Message-Id: <v04210102b7c40a6dd12b@[205.160.76.173]>
To: Pierre-Antoine CHAMPIN <champin@bat710.univ-lyon1.fr>
Cc: www-rdf-rules@w3.org
>A question has been bothering me for a while.
>In RDF we only have named nodes (with URIs) and anonymous nodes.
>So apparently the models does not enable us to create locally scoped
>names.
>
>On the other hand, the syntax has two different constructs for named
>nodes : rdf:about and rdf:ID.
>From an XML point of view, IDs are locally scoped. However, RDF makes
>them global by prepending the document URI to them, with a '#'.

Right, RDF treats anonymous nodes like locally bound existential 
variables, and all other names - URIs - as having global (WWW) scope.

>Do we agree that the same resource could have several URIS ?

Yes, but that is a different issue. Two globally scoped names may 
have the same denotation.

>I do think
>so. For example, if I write
>
><rdf:Description ID="someBook">
>  <pac:readIt>9/11/2001</pac:readIt>
>  <pac:rating>Very good</pac:rating>
></rdf:Description>
>
>I do not deny myPieceOfRDF#someBook to identify the same resource as to
>urn:isbn:12345. I may just have given it an rdf:ID for syntactical
>reasons...
>
>In short : am I wrong to use rdf:ID as a kind of locally scoped IDs?

I would say so, yes.

>If
>yes, how could I do it else? If no, how do we manage (and first of all
>recognize) those "not global URIs" in queries ?

But when prefixed with yourWebSiteAddress#, they *are* global. Why 
would they not be?

Pat Hayes

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Received on Tuesday, 11 September 2001 12:39:40 GMT

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