Re: Dumb SPARQL query problem

Not sure if this helps multilingual pigs as much as it should, but I'm not much good before coffee and expect there are many fellow mammals who share my plight ...

Language classification code reduction (in old fashioned SQL)
http://www.rustprivacy.org/faca/languages.php


--------------------------------------------
On Sat, 11/23/13, Hugh Glaser <hugh@glasers.org> wrote:

 Subject: Re: Dumb SPARQL query problem
 To: "Richard Light" <richard@light.demon.co.uk>
 Cc: "public-lod community" <public-lod@w3.org>
 Date: Saturday, November 23, 2013, 9:17 AM
 
 Pleasure.
 Actually, I found this:
 http://answers.semanticweb.com/questions/3530/sparql-query-filtering-by-string
 
 I said it is a pig’s breakfast because you never know what
 the RDF publisher has decided to do, and need to try
 everything.
 So to match strings efficiently you need to do (at least)
 four queries:
 “cat”
 “cat”@en
 “cat”^^xsd:string
 “cat”@en^^xsd:string or “cat”^^xsd:string@en - I
 can’t remember which is right, but I think it’s only one
 of them :-)
 
 Of course if you are matching in SPARQL you can use “…
 ?o . FILTER (str(?o) = “cat”)…”, but that its likely
 to be much slower.
 
 This means that you may need to do a lot of queries.
 I built something to look for matching strings (of course! -
 finding sameAs candidates) where the RDF had been gathered
 from different sources.
 Something like
 SELECT ?a ?b WHERE { ?a ?p1 ?s . ?b ?p2 ?s }
 would have been nice.
 I’ll leave it as an exercise to the reader to work out how
 many queries it takes to genuinely achieve the desired
 effect without using FILTER and str.
 
 Unfortunately it seems that recent developments have not
 been much help here, but I may be wrong:
 http://www.w3.org/TR/sparql11-query/#matchingRDFLiterals
 
 I guess that the truth is that other people don’t actually
 build systems that follow your nose to arbitrary Linked Data
 resources, so they don’t worry about it?
 Or am I missing something obvious, and people actually have
 a good way around this?
 
 To me the problem all comes because knowledge is being
 represented outside the triple model.
 And also because of the XML legacy of RDF, even though
 everyone keeps saying that is only a serialisation of an
 abstract model.
 Ah well, back in my box.
 
 Cheers.
 
 On 23 Nov 2013, at 11:00, Richard Light <richard@light.demon.co.uk>
 wrote:
 
 > 
 > On 23/11/2013 10:30, Hugh Glaser wrote:
 >> Its’ the other bit of the pig’s breakfast.
 >> Try an @en
 >> 
 > Magic!  Thanks.
 > 
 > Richard
 >> On 23 Nov 2013, at 10:18, Richard Light <richard@light.demon.co.uk>
 >>  wrote:
 >> 
 >> 
 >>> Hi,
 >>> 
 >>> Sorry to bother the list, but I'm stumped by
 what should be a simple SPARQL query.  When applied to
 the dbpedia end-point [1], this search:
 >>> 
 >>> PREFIX foaf: 
 >>> <http://xmlns.com/foaf/0.1/>
 >>> 
 >>> PREFIX dbpedia-owl: 
 >>> <http://dbpedia.org/ontology/>
 >>> 
 >>> SELECT *
 >>> WHERE {
 >>>     ?pers a foaf:Person .
 >>>     ?pers foaf:surname
 "Malik" .
 >>>     OPTIONAL {?pers
 dbpedia-owl:birthDate ?dob }
 >>>     OPTIONAL {?pers
 dbpedia-owl:deathDate ?dod }
 >>>     OPTIONAL {?pers
 dbpedia-owl:placeOfBirth ?pob } 
 >>>     OPTIONAL {?pers
 dbpedia-owl:placeOfDeath ?pod } 
 >>> }
 >>> LIMIT 100
 >>> 
 >>> yields no results. Yet if you drop the '?pers
 foaf:surname "Malik" .' clause, you get a result set which
 includes a Malik with the desired surname property. 
 I'm clearly being dumb, but in what way? :-) 
 >>> 
 >>> (I've tried adding ^^xsd:string to the literal,
 but no joy.)
 >>> 
 >>> Thanks,
 >>> 
 >>> Richard
 >>> [1] 
 >>> http://dbpedia.org/sparql
 >>> 
 >>> -- 
 >>> Richard Light
 >>> 
 > 
 > -- 
 > Richard Light
 
 -- 
 Hugh Glaser
    20 Portchester Rise
    Eastleigh
    SO50 4QS
 Mobile: +44 75 9533 4155, Home: +44 23 8061 5652

Received on Saturday, 23 November 2013 16:08:40 UTC