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RE: "Resource" (RDF vocabulary definitions)

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Tue, 26 Nov 2002 09:37:51 +0000
Message-Id: <5.1.0.14.0.20021126093009.0b438630@0-mail-1.hpl.hp.com>
To: "Chris Catton" <chris.catton@btopenworld.com>, "Dave Beckett" <dave.beckett@bristol.ac.uk>
Cc: "seth" <seth@robustai.net>, "www-rdf-comments" <www-rdf-comments@w3.org>

At 20:13 25/11/2002 +0000, Chris Catton wrote:
>I may be losing the plot now, but I still think this is a circular argument.

You may well be right.  I'm exporing the implications too...

>Summarising what's gone so far ...
>
><http://example.org/somepage#MotorVehicle> from an rdf document refers to an
>rdf resource.

 From RDF, not necessarily an RDF document.  The statement you are trying 
to make would be true if the RDF were embedded in HTML.

And No. That statement is not true.  As far as RDF is concerned the uriref in

  <rdf:Description rdf:about="http://example.org/somepage#MotorVehicle">

denotes whatever it would denote if one retrieved the document 
http://example.org/somepage with mimetype application/rdf+xml.  That does 
not necessarily make it a document in RDF format.  In this case it more 
likely denotes some abstract concept of one or a class of motor vehicles.


>So if I want to talk about the text on a web page I must define the URI:
>
>    http://example.org/somepage#MotorVehicle
>
>to mean the HTML fragment ...

The RDF denotation of that URIREF could be the HTML fragment.


>But I can't do this, because when I try and define it, I automatically refer
>to the resource and not the fragment

Why can't you do this?  There is some confusion going on here I can't put 
my finger on.  Why don't you try writing a test cases where you think a 
generic RDF processor could tell the difference.

>Brian McBride wrote>
> >What you need is a URI that you know refers to the html representation of
> >the resource.  I guess (YUK) we could define a urn or uri scheme for this:
>
>Does this mean we agree there is a problem? - I'm genuinely not quite sure

Yes and No.  There is a problem in that this is confusing and not easy to 
explain.

I don't think we have exposed a logical flaw or inconsistency in RDF's 
position yet.



> > I think you are into an area that properly belongs in web
> > architecture, not
> > just RDF.  What exactly does a URI, or URL for that matter identify.  We
> > architecture doesn't seem to be that well defined on this point,
> > and it is
> > all a bit tricky.
>
>Well, it's certainly a problem for more than just rdf, but the semantic web
>aint gonna work if we try to get a ticket to london on a text string or
>print out a bus :-)

Just so.

Brian
Received on Tuesday, 26 November 2002 04:36:28 GMT

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