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RE: "Resource" (RDF vocabulary definitions)

From: Chris Catton <chris.catton@btopenworld.com>
Date: Mon, 25 Nov 2002 13:17:01 -0000
To: "Brian McBride" <bwm@hplb.hpl.hp.com>, "Dave Beckett" <dave.beckett@bristol.ac.uk>
Cc: "seth" <seth@robustai.net>, "www-rdf-comments" <www-rdf-comments@w3.org>
Message-ID: <OKEMLMGGGDAEEGEAKOBHCENCCEAA.chris.catton@btopenworld.com>

(This thread began in rdf interest)

OK, my understanding is deepening I think, but I also think there is still
be a problem here.

In my *rdf* document I write
<http://example.org/somepage#MotorVehicle>  rdf:type
<http://example.org#HtmlFragment>

In my *html* document at http://example.org/somepage, i can write (stupidly
perhaps, but perfectly legally)

<a name="MotorVehicle">model t ford type thing</a>

and in the header on the same page (as suggested at
http://www.w3.org/RDF/FAQ#How )

<rdf:Description rdf:ID="MotorVehicle">
  <rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
  <rdfs:subClassOf
rdf:resource="http://www.w3.org/2000/01/rdf-schema#Resource"/>
</rdf:Description>

Now:
1.	My html document is referred to from an rdf document and so treated as an
rdf document. (stated in http://www.w3.org/TR/rdf-concepts/#xtocid103660 )
2.	As an rdf document a reference to
http://example.org/somepage#MotorVehicle refers to whatever the owner of
http://example.org says it is - her car perhaps.
3. 	Her car is not an HtmlFragment - so we have a category error.

So I don't see how I can reliably reference an html fragment from an rdf
document. Common sense might tell us what was meant, but I don't see the
rules that let a machine decide. Anyone see a way out of this?  Paul
Prescods post Re: a URI is a name (tel uri scheme and VCARD RDF) on
rdf-interest suggests we don't need 2 URIs because we can use rdf to
distinguish the meaning.  If we cannot actually reference the fragment
reliably, this is not true.

C


> -----Original Message-----
> From: Brian McBride [mailto:bwm@hplb.hpl.hp.com]
> Sent: 25 November 2002 11:10
> To: Dave Beckett; Chris Catton
> Cc: seth; www-rdf-comments
> Subject: Re: "Resource" (RDF vocabulary definitions)
>
>
> Response not crossposted:
>
> At 10:06 25/11/2002 +0000, Dave Beckett wrote:
>
> [...]
>
> > > Does this mean that if I represent a graph in rdf/xml inside an html
> > > document by putting some triples inside rdf tags it has a completely
> > > different meaning to a graph expressed in exactly the same way but
> > served as
> > > an .rdf document?
>
> I said somthing like that once and Graham Klyne pointed out my
> error to me.
>
> If I have some HTML containing say:
>
>    <rdf:Description rdf:about="http://example.org/something#foo">
>       ...
>
> The issue here is about what http://example.org/something#foo names.  The
> meaning of this is not dependent on the mimetype of the referring
> document,
> e.g. text/html, but on the mime-type of the *retrieved* document.
>  The RDF
> specs are saying that for determining the RDF meaning of this
> uriref, it is
> the meaning that would be assigned by retrieving a document of mime-type
> application/rdf+xml.
>
> Embedding in a document of mime-type text/html does not affect this.
>
> Brian
>
Received on Monday, 25 November 2002 08:22:34 GMT

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