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RE: Reqirement 3.5: subgraph results

From: Dan Connolly <connolly@w3.org>
Date: Tue, 04 May 2004 16:07:50 -0500
To: Rob Shearer <Rob.Shearer@networkinference.com>
Cc: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Message-Id: <1083704869.460.897.camel@dirk>

On Tue, 2004-05-04 at 15:45, Rob Shearer wrote:
> > >  in fact it
> > > codifies that any such extension is explicitly illegal. 
> > Queries along
> > > the lines of "must these two nodes be related via either of 
> > these two
> > > properties?" suddenly become impossible to answer when that 
> > answer is
> > > derived via inference, or rules, or some higher-level 
> > semantic language.
> > 
> > I don't understand how you come to that conclusion.
> > 
> > Our charter addresses this pretty clearly, no?
> > 
> > "1.8 Derived Graphs
> > 
> > The working group must recognize that RDF graphs are often constructed
> > by aggregation from multiple sources and through logical 
> > inference, and
> > that sometimes the graphs are never materialized. Such graphs may be
> > arbitrarily large or infinite."
> >  -- http://www.w3.org/2003/12/swa/dawg-charter#derivedGraphs
> 
> "Logical inference" extends a *lot* farther than just appending triples
> to an RDF graph.
> There are a lot of ways to say "at least one of these two edges needs to
> exist".

Aha! Now I get it. Thanks for spelling it out (again? several
times now?)

Gee... I was being pretty dense.

Hmm... I think I need to talk this over with a few other people
that were involved in writing the charter.

Meanwhile, I can see your point about this requirement.

I leave it to the advocates to try to convince you.

>  It can be a consequence of an OWL ontology; it can be a
> consequence of a rule encoded in a rules language; it can be a
> consequence of any semantic layer you want to put on top of the basic
> RDF data model. It does explicitly say something about what RDF graphs
> are possible and what are not. But such knowledge does not necessarily
> have any sensible encoding in RDF itself.

[...]


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
see you at the WWW2004 in NY 17-22 May?
Received on Tuesday, 4 May 2004 17:07:47 GMT

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