- From: Bernard Vatant <bernard.vatant@mondeca.com>
- Date: Tue, 21 Oct 2008 12:27:37 +0200
- 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 SKOS version declared in the namespace is the 2004 version, which is now superseded by the new 2008 SKOS specification and namespace.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, cité Nollez 75018 Paris France Web: www.mondeca.com <http://www.mondeca.com> Blog: Leçons de Choses <http://mondeca.wordpress.com/> ----------------------------------------------------**
Received on Tuesday, 21 October 2008 10:28:34 UTC