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From: Christoffel Dhaen <christoffel@landcglobal.com>
Date: Mon, 12 Dec 2005 16:16:15 +0100
Message-ID: <28A0FFC7AEF0014AA8C2CE543AE13F5B53D355@x-box.quest.net>
To: "Enrico Franconi" <franconi@inf.unibz.it>
Cc: "McBride, Brian" <brian.mcbride@hp.com>, "David Wood" <dwood@softwarememetics.com>, "Pat Hayes" <phayes@ihmc.us>, "Christopher Welty" <welty@us.ibm.com>, <public-swbp-wg@w3.org>

Ah, then I rest my case.
I just got the impression that this was not possible on the same graph.
As Brain stated:

"I earlier suggested that SPARQL does not have to support transitive closure because the graph can do it.  There can be an inferencing graph which computes the transitive closure of skos:narrower.  If you query that graph you query the transitive closure relationship.  If you query the ground graph you get the direct, well at least directly asserted, relationship."

I got the impression that 2 graphs would be needed if direct and indirect relations had to be taken into account. But if I understand correctly, the transitive nature of subPropertyOf and subClassOf is being taken into account, but the owl:transitiveProperty is not. I got the impression that transitivity was not taken into account at all, not even for subPropertyOf and subClassOf, and queries were only possible on direct assertions, which was my main concern. 

Case closed, I guess.


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> -----Original Message-----
> From: Enrico Franconi [mailto:franconi@inf.unibz.it]
> Sent: maandag 12 december 2005 15:39
> To: Christoffel Dhaen
> Cc: McBride, Brian; David Wood; Pat Hayes; Christopher Welty; public-swbp-
> wg@w3.org
> Subject: Re: [SKOS, SPARQL, ALL] Closure and SPARQL
> On 12 Dec 2005, at 15:23, Christoffel Dhaen wrote:
> > HasPet subPropertyOf Likes
> > Person subClassOf Animal
> > Woman subClassOf Person
> > OldLady subClassOf Woman
> > OldLady HasPet Cat
> > Cat subClassOf Animal
> >
> > A query
> > (X subClass Person) AND (X Likes Animal)
> > gives the answer
> > {X= OldLady}
> >
> > This takes the class-hierachy into account, as wel as the property
> > hierachy.
> >
> > Unless I have I missed this somewhere, according to the
> > specifications, the query on this graph would not give this result
> > and the resultset would be empty.
> >
> > I would say "simple RDf entailment" and "RDF entailment" entailment
> > as you point out in 2) should be possible on the same graph, but I
> > got the impression that this is not possible.
> > 1) can be resolved by doing a minus between the entailment and the
> > simple entailment results.
> According to the current state of discussion in the DAWG, the use of
> "simple RDF entailment" and "RDF entailment" is possible and it would
> actually capture what you want as you point out.
> cheers
> --e.
> --
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Received on Monday, 12 December 2005 15:16:52 UTC

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