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Fw: Summary: URIs : How to find the ontologies behind them

From: Eli Israel <Eli@SemanticWorld.Org>
Date: Thu, 10 Apr 2003 11:59:59 +0300
Message-ID: <018501c2ff3f$90aa5620$5c14a8c0@unicorn.co.il>
To: <Patrick.Stickler@nokia.com>
Cc: <www-rdf-interest@w3.org>

 Patrick,
 
    I'm intrigued by what you've written, but I want to make sure that I
 understand it fully.  What do you mean by the term "web authority of the
 URIref"?
 
 Eli
> 
> ----- Original Message -----
> From: <Patrick.Stickler@nokia.com>
> To: <pfps@research.bell-labs.com>; <Eli@semanticworld.org>
> Cc: <www-rdf-interest@w3.org>
> Sent: Thursday, April 10, 2003 9:40 AM
> Subject: RE: URIs : How to find the ontologies behind them
> 
> 
> 
> > > I'm primarily interested in the 'when the SW gets going'
> > case (it's about
> > > time we get it going, no? ;).  You seem to be saying that a
> > best practice
> > > would be to put the OWL describing the resource in the
> > place that the URI of
> > > the resource refers to.
> >
> > Not necessarily in that exact place.  However, most RDF URI
> > references have
> > fragment identifiers, so it would be possible for example to place
> > information about http://foo.ex/bar#bax in a document located at
> > http://foo.ex/bar.
> 
> Sorry. Unfortunately, no.
> 
> RDF fragment IDs do not work in exactly the same way as XML ID's.
> 
> You can describe the resource http://foo.ex/bar#bax in a dozen
> different RDF/XML instances, none of which are http://foo.ex/bar.
> And in all cases, you need not use rdf:ID ever. So even if
> http://foo.ex/bar#bax is defined by http://foo.ex/bar, that
> doesn't guaruntee that rdf:ID="bax" occurs anywhere in that
> RDF/XML instance.
> 
> And there is no assertion that http://foo.ex/bar#bax relates to
> a particular XML *element* in an RDF/XML instance having an
> rdf:ID="bax" even if the parser will map such an rdf:ID value
> to a URI based on an xml:base separated by '#'. rdf:ID is
> not defined as an XML ID attribute.
> 
> And in fact, though there should only be one occurrence of a given
> rdf:ID value for an xml:base scope, one can have descriptions using
> both rdf:ID and rdf:about about the very same resource in the same
> RDF/XML instance.
> 
> One should not think of URIrefs as working in RDF the same way
> as they do in an HTML browser. They don't.
> 
> Thus, just as one cannot reliably get to a namespace document
> from a URI, one cannot get to a definitive RDF/XML instance from
> a URIref.
> 
> *** TAKE NOTE: URIrefs are *fully opaque* in an RDF graph and SW
> *** agents operating on RDF expressed knowledge should not attempt
> *** to parse URIrefs to infer any relationships between the resource
> *** denoted by the URIref and any other resource that might share
> *** some intersection of some character sequence with the URIref.
> 
> The SW deals with RDF graphs, not RDF/XML instances, so
> one should not be concerned with aspects of the XML serialization
> when requesting knowledge from a knowledge base. And looking
> at URI vs. URIref or URI vs. namespace relations (neither of
> which can be reliably utilized) is the wrong way to go.
> 
> The SW architecture should provide for a standardized means by
> which, given a URIref, one can inquire from the web authority
> of the URIref (presuming there is one) for a description of
> the resource denoted by the URIref.
> 
> One can also inquire from various registries or other sources
> for non-web-authoritative descriptions of the resource, allowing
> for one to syndicate various views and opinions of the resource.
> 
> URIQA will provide for both.
> 
> > ... I think that the
> > relationship between ontologies and URI references is many to
> > many (and
> > many to many in interesting ways).
> 
> Agreed.
> 
> Patrick
> 
> --
> Patrick Stickler, Nokia/Finland, (+358 40) 801 9690,
> patrick.stickler@nokia.com
> 
Received on Thursday, 10 April 2003 05:00:02 GMT

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