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Re: Looking for churches in Paris - skos:broader transitivity and dbpedia categories

From: Sean Bechhofer <sean.bechhofer@manchester.ac.uk>
Date: Tue, 21 Oct 2008 11:53:49 +0100
Message-Id: <AED82AD7-32EB-4359-AABA-7F67D6E1CAB3@manchester.ac.uk>
Cc: dbpedia-discussion@lists.sourceforge.net, SKOS <public-esw-thes@w3.org>, SWD Working SWD <public-swd-wg@w3.org>
To: Bernard Vatant <bernard.vatant@mondeca.com>


On 21 Oct 2008, at 11:27, Bernard Vatant wrote:

>
> Hi all
>
> I wanted to get at the following data set through http:// 
> dbpedia.org/sparql
>
> "Churches in Paris, along with French name and description, and geo- 
> tagging elements"
>
> The category "Churches in Paris" has typically two levels of  
> subcategories, by "Religion", then by "Arrondissement"
>
> So the following query
>
> PREFIX p: <http://dbpedia.org/property/>
> PREFIX dbpedia: <http://dbpedia.org/resource/>
> PREFIX category: <http://dbpedia.org/resource/Category:>
> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
> PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
> PREFIX geo: <http://www.georss.org/georss/>
>
> SELECT DISTINCT ?m ?n ?p ?d
> WHERE {
>     ?m rdfs:label ?n.
>     ?m skos:subject ?c.
>     ?c skos:broader category:Churches_in_Paris.
>     ?m p:abstract ?d.
>     ?m geo:point ?p
>    FILTER ( lang(?n) = "fr" )
>    FILTER ( lang(?d) = "fr" )}
>
> ... yields only the two results which are in a direct subcategory.  
> Which means skos:broader transitivity is not supported. OK.
> This leads to several remarks and questions.
> SKOS version declared in the namespace is the 2004 version, which  
> is now superseded by the new 2008 SKOS specification and namespace.
> For those not aware of the long debate history in SKOS about  
> broader transitivity, the sum up is as following
>
> skos(2004):broader is transitive
> skos(2008):broader is no more transitive. It links only to the  
> direct parent.
> skos(2008):broaderTransitive is a superproperty of the above, and  
> it is transitive - like skos(2004):broader
>
> To sum it up, the current dbpedia interface declares skos:broader  
> in the 2004 namespace, but de facto applies the 2008 semantics (no  
> transitivity).
> This is indeed confusing, and given there has been already a lot of  
> confusion in people minds about that affair, it's too bad.
> Has dbpedia in project to switch from SKOS 2004 to SKOS 2008  
> namespace and semantics, and if yes when? And in such a case case,  
> will it support skos2008:broaderTransitive queries? As a side note,  
> skos:subject is deprecated in SKOS 2008


FYI, the question of the SKOS namespace is still under discussion,  
and is an issue raised during the  Last Call period [1,2]. Input to  
the discussion from implementors would be most welcome.

Thanks,

	Sean

[1] http://www.w3.org/2006/07/SWD/track/issues/153
[2] http://www.w3.org/2006/07/SWD/track/issues/175

--
Sean Bechhofer
School of Computer Science
University of Manchester
sean.bechhofer@manchester.ac.uk
http://www.cs.manchester.ac.uk/people/bechhofer
Received on Tuesday, 21 October 2008 10:55:27 GMT

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