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Re: ACTION: task force unasserted triples

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Tue, 23 Apr 2002 12:31:25 -0500
Message-Id: <p05101517b8eb472697af@[65.217.30.94]>
To: Dan Connolly <connolly@w3.org>
Cc: www-webont-wg@w3.org
>
>>  If, however, the triples that are used to encode the syntax of the
>>  constructs of the WebOnt language are unasserted,
>
>HOW?
>
>Please spell out the (proposed) solution completely.

That is the RDF core WG's task, surely, as things stand at the 
moment. Of course if that WG tells WebOnt to get stuffed, then it 
would become our problem once again

>Show the actual RDF/XML that is used in the (proposed) solution.
>
>Show how one can differentiate the asserted triples from
>the unasserted triples.

You know there have been several proposals for HOW to do it.  We 
can't even get to that point if we have to keep persuading the 
coordination group why it needs doing at all.  (I feel a bit like an 
engineer trying to persuade the design oversight committee that we 
really do need a tube from the fuel tank to the engine, and they keep 
asking what effect it is going to have on the color of the 
paintwork.)  But OK, here's a proposal: we provide some way to 
indicate that a given namespace is dark (I'll leave the exact XML 
syntax for this to someone else: invent something that leaves some 
recognizable and unambiguous trace in the RDF graph.) Then the rule 
is that any triple containing any uriref from that namespace is dark. 
The appropriate choice for DAML for example would be to darken the 
daml:list/daml:first/daml:last vocabulary.

>Fill in enough details that the RDF Core WG can evaluate
>the costs of such a mechanism (and so that they can
>consider nearby alternatives).

There would be almost no cost to RDF, as far as I can see, other than 
a commitment to regard the 'darkening' assertions as part of the 
graph, so they will be preserved when round-tripping through RDF. It 
could be actually done *in* RDF, by having a special rdfs 
pseudo-class called rdf:dark, for example. If WebOnt has to do it, 
then we could introduce owl:dark and do it ourselves, and just ignore 
what the RDF MT says it means. That would still be a flaw in the neat 
layering, but at least it will keep all the dirt in one place.

>  > then these constructs do
>>  not need to be part of the domain of discourse.  In this case, there is no
>>  need for comprehension axioms, and a non-trivial theory can be developed for
>>  the WebOnt language.
>>
>>
>>  What is lost?  Well, of course, quite a number of entailments are lost, and
>>  the details depend on which triples are unasserted.
>
>Which triples do you/we propose are unasserted?

See above.

Pat
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Received on Tuesday, 23 April 2002 13:31:28 GMT

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