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RE: Unasserted triples, Contexts and things that go bump in the night.

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Wed, 20 Mar 2002 11:32:04 -0000
To: "Patrick Stickler" <patrick.stickler@nokia.com>, "Pat Hayes" <phayes@ai.uwf.edu>, "RDF Core" <w3c-rdfcore-wg@w3.org>
Message-ID: <JAEBJCLMIFLKLOJGMELDMEGPCDAA.jjc@hplb.hpl.hp.com>
Pat:
> >> Another possibility is to allow certain namespaces to be declared to
> >> be dark, so that any triple using a property from a dark namespace is
> >> considered to be unasserted. Again, this does not require any change
> >> to the syntax, but only some extra conventions to be added to the
> >> language.
> >>
Jeremy:
> > This could be a namespace prefix rather than the namespace e.g.
> >
> >
> > <rdf:RDF xmlns:eg="http://example.org/"
> xmlns:egdark="http://example.org/"
> >        rdf:darkPrefixes="egdark">
> >    <rdf:Description eg:aserted="foo" egd:unasserted="bar" />
> >
> > </rdf:RDF>
> >
> > Jeremy
Patrick:
> This becomes problemmatic (in a practical sense) if we want to
> use the same vocabularies for both asserted and unasserted
> statements.

A fair point ... my example is bad stylistically, but does show that the XML
syntax is as flexible as the n-triple syntax.

Patrick:
> An alternative:
>
> How about an element rdf:Expression (or some such) which is in all
> other ways identical to rdf:Description except that statements
> are not asserted. E.g.
>
>    <rdf:Expression rdf:about="#Bob>
>       <ex:age>35</ex:age>
>    </rdf:Expression>
>
> gives us
>
>     :Bob ex:age "35" ;
> or
>     - :Bob ex:age "35" .
>
> This doesn't require any significant changes to current parsers
> and the only modification is to activate a flag when seeing
> rdf:Expression rather than rdf:Description and add the non-asserted
> punctuation when outputting the triples.

This too is a fair syntax ....

I suspect somewhat more confusing though ...

We still can get the confusion of using the same vocab both ways ...

e.g.

<rdf:RDF>
  <rdf:Expression rdf:about="#Bob>
      <ex:age>35</ex:age>
   </rdf:Expression>
  <rdf:Description rdf:about="#April>
      <ex:age>35</ex:age>
   </rdf:Description>
</rdf:RDF>


and would need clarity about embedding


e.g.

<rdf:RDF>
  <rdf:Description rdf:about="#April>
      <ex:foo>
       <rdf:Expression rdf:about="#Bob>
          <ex:bar ex:doublyEmbedded="??"/>
        </rdf:Expression>
    </ex:foo>
  </rdf:Description>
</rdf:RDF>

that clarity could be done (I would favour a one level reading like for
bagID).


Jeremy
Received on Wednesday, 20 March 2002 06:33:34 EST

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