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Re: Formal Semantics of OWL + RDF + SPARQL + SWRL

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Tue, 06 Dec 2005 10:26:08 -0500 (EST)
Message-Id: <20051206.102608.62315001.pfps@research.bell-labs.com>
To: danny.ayers@gmail.com
Cc: adrianw@snet.net, semantic-web@w3.org

From: Danny Ayers <danny.ayers@gmail.com>
Subject: Re: Formal Semantics of OWL + RDF + SPARQL + SWRL
Date: Tue, 6 Dec 2005 10:47:59 +0100

> On 12/6/05, Adrian Walker <adrianw@snet.net> wrote:
> 
> I suspect Peter has a different point of view that I on this, but for
> what it's worth:
> 
> > A thought about "those were not the results I expected" and SPARQL...
> >
> > One of the bad things about the various implementations of classical SQL is
> > that they have divergent semantics -- that is, they can produce different
> > results given the same query and data.
> 
> Quite. Although the idea that a store should include inferred triples
> in response to a query is appealing, I think the problems are likely
> to outweigh the benefits.
> 
> I'm sure we will continue to see plenty of RDF-only stores, so the
> only way systems could operate consistently would be at that level -
> i.e. the query will only be over the statements explicitly asserted. I
> don't know how straightforward that is to capture formally (Peter?)
> but pragmatically I'm not sure there's much choice.

Well, even an RDF-only store *should* be respecting the RDF semantic, which
does have some non-trivial inferences.

> But this doesn't rule out the potential for stores to provide extra
> query endpoints, e.g.
> http://example.org/query
> http://example.org/apply-class-subsumption-then-query
> http://example.org/apply-rdfs-rules-then-query
> http://example.org/apply-owl-rules-then-query

I agree that there is the possibility of allowing stores that have different
functionality.  I do not believe, however, that the current vision of the
Semantic Web supports a good way of providing this.

> Cheers,
> Danny.

peter
Received on Tuesday, 6 December 2005 15:26:51 GMT

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