Alexandre Passant wrote: > Hi, > > On 8 Oct 2009, at 16:54, Kingsley Idehen wrote: > >> Antoine Isaac wrote: >>> Alexandre Passant a écrit : >>>> Hi, >>>> >>>> On 8 Oct 2009, at 16:09, Kingsley Idehen wrote: >>>> >>>>> All, >>>>> >>>>> The intersection of Leigh Dodds SPARQL extensions survey [1], >>>>> imminent official release of Virtuoso 6.0 (DBpedia basic and Live >>>>> already use this, ditto LOD Cache, and B3S public endpoints), and >>>>> an old post by Bernard Vatant re. skos:broader, has lead to this >>>>> simple, but powerful example of Virtuoso's Transitive Option >>>>> extension for SPARQL : >>>>> >>>>> #Transitive Option Off >>>>> >>>>> 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" ) >>>>> } >>>>> >>>>> #Transitive Option On >>>>> >>>>> 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 OPTION (TRANSITIVE). >>>>> ?m p:abstract ?d. >>>>> ?m geo:point ?p >>>>> FILTER ( lang(?n) = "fr" ) >>>>> FILTER ( lang(?d) = "fr" ) >>>>> } >>>>> >>>>> >>>> >>>> As skos:broader is not transitive [1] but its superproperty >>>> skos:broaderTransitive is, shouldn't the second query be >>>> >>>> ?c skos:broaderTransitive category:Churches_in_Paris OPTION >>>> (TRANSITIVE). >>>> >>>> Best, >>>> >>>> Alex. >>>> >>>> [1] http://www.w3.org/TR/2009/REC-skos-reference-20090818/#L2413 >>> >>> >>> +1. Also, skos:subject is not in the recommendation... >> >> Fine, but what happens when the data in question already has such >> triples? Try this against DBpedia: >> >> 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:broaderTransitive category:Churches_in_Paris option >> (transitive) . >> ?m p:abstract ?d. >> ?m geo:point ?p >> FILTER ( lang(?n) = "fr" ) >> FILTER ( lang(?d) = "fr" ) >> } >> >> You will have an empty result-set. Again, this is the point Bernard >> Vatant made in his post a long time ago. > > So there is something wrong in the current inference done in DBPedia. > Indeed, that query lists one result > > 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" ) > } > > But the following one list none > > 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:broaderTransitive category:Churches_in_Paris . > ?m p:abstract ?d. > ?m geo:point ?p > FILTER ( lang(?n) = "fr" ) > FILTER ( lang(?d) = "fr" ) > } > > However, skos:broaderTransitive is a superproperty of skos:broader, so > you should get at least the result of the first query included here. Only if you have a Virtuoso context rule in place (the kind I created for Yago, UMBEL, OpenCyc, DBpedia ontology etc..) that is associated with a Graph IRI that holds the assertions. Thus, in this case, I would have to do the following:
1. Load SKOS ontology into Virtuoso instance hosting DBpedia 2. Associate a context rule with the Graph IRI 3. When issuing SPARQL or associating SPARQL with URL-Rewrite rules, invoke the inference rule pragma. If you look at: http://dbpedia.org/fct or http://lod.openlinksw.com/fct, post initial query result presentation, you have an "options" link, this is where you can see the context rules that are currently available. In short, this is what I use (e.g. "b3sifp") for my data reconciliation via direct and indirect co-reference demos. Anyway, we'll have this all set up, then and make another post so everyone has the respective rule names for future reference and use. Kingsley > Then, the query you mentioned earlier (using option (transitive) with > skos:broaderTransitive) should not give an empty set - and everything > work fine. > > Thanks, > > Alex. > > BTW, do you have a link to Bernard's post ? > >> Ultimate solution: make an inference rule that asserts: >> <skos:broaderTransitive> owl:subPropertyOf <skos:broader> (or make a >> context rule from the entire skos ontology), and you will then have >> the revised query return data for those databases that have used >> skos:broader to build their concept scheme structure (assuming you >> apply the inference rule pragma). Otherwise, If your store has >> skos:broaderTransitive data, then just change the query :-) > >> >> Kingsley >>> >>> Best, >>> >>> Antoine >>> >>> >> >> >> -- >> >> >> Regards, >> >> Kingsley Idehen Weblog: http://www.openlinksw.com/blog/~kidehen >> President & CEO OpenLink Software Web: http://www.openlinksw.com >> >> >> >> > > -- > Dr. Alexandre Passant > Digital Enterprise Research Institute > National University of Ireland, Galway > :me owl:sameAs <http://apassant.net/alex> . > > > > > > > -- Regards, Kingsley Idehen Weblog: http://www.openlinksw.com/blog/~kidehen President & CEO OpenLink Software Web: http://www.openlinksw.com ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Dbpedia-discussion mailing list Dbpedia-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dbpedia-discussion
