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

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Tue, 21 Oct 2008 12:27:37 +0200
Message-ID: <48FDAE99.4000504@mondeca.com>
To: dbpedia-discussion@lists.sourceforge.net
CC: SKOS <public-esw-thes@w3.org>

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superseded by the new 2008 SKOS specification and namespace.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.

Back to my churches in Paris, is there currently a workaround to get the 
results for all subcategories in a single query?

Thanks for your attention.

-- 

*Bernard Vatant
*Senior Consultant
Vocabulary & Data Engineering
Tel:       +33 (0) 971 488 459
Mail:     bernard.vatant@mondeca.com <mailto:bernard.vatant@mondeca.com>
----------------------------------------------------
*Mondeca**
*3, citÚ Nollez 75018 Paris France
Web:    www.mondeca.com <http://www.mondeca.com>
Blog:    Lešons de Choses <http://mondeca.wordpress.com/>
----------------------------------------------------**
Received on Tuesday, 21 October 2008 10:28:34 GMT

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