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RE: Dark triples motivation

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Wed, 17 Apr 2002 18:33:35 -0500
Message-Id: <p05101515b8e3b6b3ab00@[65.217.30.94]>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Cc: www-webont-wg@w3.org
>  >
>>  I did my best at:
>>
>>  http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Apr/0178.html
>>
>
>
>In light of the feedback, I have been clarifying my idea of what the problem
>is.
>
>Problem statement:
>
>Layering on top of RDF involves using graph syntax to encode OWL concepts.
>If such graph syntax is asserted then the RDF model theory assigns meaning
>to such syntax specifically denoting things in the domain of discourse that
>correspond to the syntactic expressions of OWL. Given this, an OWL model
>theory with appropriate entailments (in which the theory of classes in OWL
>is recognisable as a subtheory of some well known set theory) is difficult
>and problematic to construct.
>
>
>Solution statement:
>
>Using unasserted triples for the syntactic structures of OWL allows an OWL
>interpretation to assign a meaning to a subgraph which need bear no
>correspondence with the meaning of corresponding asserted triples in RDF.
>
>
>
>Example:
>
>The RDF document:
>
><rdf:Description rdf:about="#John">
>    <rdf:type rdf:resource="#Student">
>    <rdf:type rdf:resource="#Employee">
></rdf:Description>
>
>understood with rdf:type denoting set membership, would, under almost all
>set theories, entail #John being a member of the intersection of #Student
>and #Employee.
>In daml+oil this is said:
>
><rdf:Description rdf:about="#John">
>    <rdf:type>
>     <daml:class>
>       <daml:intersectionOf rdf:parseType="daml:collection">
>          <daml:class rdf:ID="Employee"/>
>          <daml:class rdf:ID="Student"/>
>      <daml:intersectionOf>
>     </daml:class>
>    </rdf:type>
></rdf:Description>
>
>If we leave the daml class expression:
>
>
><rdf:RDF>
>     <daml:class>
>       <daml:intersectionOf rdf:parseType="daml:collection">
>          <daml:class rdf:ID="Employee"/>
>          <daml:class rdf:ID="Student"/>
>      <daml:intersectionOf>
>     </daml:class>
></rdf:RDF>
>
>as unasserted then OWL can assign a meaning to this expression wholly
>independently of RDF.
>
>
>Have I got it?

That seems a fair summary to me, yes.

Pat

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Received on Wednesday, 17 April 2002 19:33:39 GMT

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