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Re: Reification quoting in RDF/N3 was: A note comparing Conceptual Graphs and RDF/Semantic Web

From: Tim Berners-Lee <timbl@w3.org>
Date: Thu, 18 Jan 2001 10:40:00 -0500
Message-ID: <050301c0825b$fc3d1430$0301a8c0@w3.org>
To: "McBride, Brian" <bwm@hplb.hpl.hp.com>, <www-rdf-logic@w3.org>
Cc: <danbri@w3.org>

----- Original Message -----
From: "McBride, Brian" <bwm@hplb.hpl.hp.com>
To: "Tim Berners-Lee" <timbl@w3.org>; <www-rdf-logic@w3.org>
Cc: <danbri@w3.org>
Sent: Thursday, January 18, 2001 6:55 AM
Subject: RE: Reification quoting in RDF/N3 was: A note comparing Conceptual
Graphs and RDF/Semantic Web


> [snip]
>
> > However, in the RDF syntax there is a known problem there.
> > You can't quote
> > something without asserting it.
>
> I'm not sure I understand the problem.  Simplifying your
> example for clarity:
>
>   <rdf:RDF>
>     <rdf:Statement>
>       <rdf:subject    rdf:about="mary"/>
>       <rdf:predicate  rdf:about="wants to marry"/>
>       <rdf:object     rdf:about="Fred"/>
>       <foo:believedBy rdf:about="John"/>
>     </rdf:Statement>
>   </rdf:RDF>
>
> as I understand things, the above quotes
> (wants to marry, mary, Fred) without asserting it, if
> I understand correctly what you mean by 'quotes'.
>
> Please could you give a concrete example of the bug you
> had in mind?

Oh, I agree that it is fine if you express the reified form.
What you can't do is:

<rdf:rdf>
   <rdf:description bagID="a" about="#Mary">
      <foo;wantstomarry resource="#Fred"/>
  </rdf:description>
  <rdf:description about="#John">
      <bar:believes resource="#a"/>
</rdf:rdf>

without asserting #a.   The unreified form is of course much more paletable.
A simple extension to fix this would be:

<rdf:rdf>
   <rdf:quote ID="a">
      <rdf:description about="#Mary">
         <foo;wantstomarry resource="#Fred"/>
      </rdf:description>
  </rdf:quote>
  <rdf:description about="#John">
      <bar:believes resource="#a"/>
</rdf:rdf>

TimBL


> Brian McBride
> HPLabs
>
Received on Friday, 19 January 2001 16:04:29 GMT

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