W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > April 2002

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

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Fri, 5 Apr 2002 15:02:24 -0600
Message-Id: <p05101509b8d3bff8cbf6@[]>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Cc: <w3c-rdfcore-wg@w3.org>, <www-webont-wg@w3.org>
>  > >My point being that using dark triples to construct purely syntactic
>>  >substructures within RDF graphs then begs the question of how to describe
>>  >the syntax of those syntactic substructures.
>>  Well, it doesn't address that question, but then it doesn't address a
>>  whole lot of other questions either. It wasn't aimed at that issue. I
>>  don't think it would interfere with any proposals along that
>>  direction, however.
>I was not clear enough - I would find it much easier to support a dark
>triples proposal that looked like a general purpose extension mechanism for
>RDF rather than one that was a special fudge for OWL.

Fair enough, though I do think that dark triples is what might be 
called a general-purpose fudge for layering anything on top of RDF. I 
would myself vastly prefer to redefine RDF altogether to give it the 
ability to describe arbitrary recursive syntax trees, but I felt that 
at this stage in the RDF WG's activities it was wisest to keep the 
changes to the absolute minimum required. Notice that the dark 
triples proposal is not incompatible with any more elaborate 
proposals that might be made later.

>Requiring the syntax of an extension to be described in English rather than
>in a machine readable way

?? Nobody is proposing that, I think. If we can come up with some 
syntactic way to indicate darkness of triples, then that is all that 
RDF needs to do. Then OWL can use its own syntactic conventions to 
distinguish those triples which encode its own constructs, and mark 
them as dark. That is all that is required to prevent the kind of 
layering problems that Peter is so concerned about.

>takes us back to things like rdf:parseType being
>an extension mechanism that fails to give any true extensibility (because an
>RDF parser doesn't know how to read the english in the daml spec that
>descibes the extension of parseType="daml:collection").

I agree that would be regrettable, but that isnt part of the proposal.


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Received on Friday, 5 April 2002 16:02:24 UTC

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