Hi,
I loaded parts of the DBpedia dataset into my local Virtuoso instance.
The version is Virtuoso version 07.10.3211 on Linux
(x86_64-unknown-linux-gnu), Single Server Edition .
The endpoint is available at
http://akswnc3.informatik.uni-leipzig.de:8860/sparql
When I run the query (see http://tinyurl.com/qhdzlbg )
describe(<http://dbpedia.org/resource/Bumblehood>)
to get triples about a specific resource, I get
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix dbpedia: <http://dbpedia.org/resource/> .
@prefix ns2: <http://schema.org/> .
dbpedia:Bumblehood rdf:type ns2:Organization .
@prefix ns3: <http://www.ontologydesignpatterns.org/ont/dul/DUL.owl#> .
dbpedia:Bumblehood rdf:type ns3:SocialPerson .
@prefix ns4: <http://dbpedia.org/ontology/> .
dbpedia:Bumblehood rdf:type ns4:Company .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
dbpedia:Bumblehood rdf:type owl:Thing ,
ns3:Agent ,
ns4:Organisation ,
ns4:Agent .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
dbpedia:Bumblehood ns4:formationDate "2009-02-15+02:00"^^xsd:date ;
ns4:keyPerson dbpedia:Chief_executive_officer ;
ns4:location dbpedia:Zagreb ,
dbpedia:Moscow ,
dbpedia:Munich ;
ns4:numberOfEmployees 17 ;
ns4:type dbpedia:Privately_held_company .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
dbpedia:Bumblehood foaf:homepage <http://www.bumblehood.com/> ;
foaf:name "Bumblehood, Inc."@en .
Now suppose I want to go into the inverse direction, that means I run a
query (see http://tinyurl.com/of472dp ) to get all resources that have
the same formation date, i.e.
SELECT DISTINCT ?s WHERE {
?s <http://dbpedia.org/ontology/formationDate>
"2009-02-15+02:00"^^<http://www.w3.org/2001/XMLSchema#date>.
}
it returns an empty set. I know that there are some problems with dates,
but I don't get the point here, because date literals are returned but
can not be used to match the same resource.
I read about some workarounds like filtering by the lexical form, e.g.
SELECT DISTINCT ?s WHERE {
?s <http://dbpedia.org/ontology/formationDate> ?date.
FILTER(STR(?date) = "2009-02-15+02:00")
}
but that also does not work (see http://tinyurl.com/pmuu5fr*)*. It only
works if I use a different lexical form and omit the timezone
information from the string, like
SELECT DISTINCT ?s WHERE {
?s <http://dbpedia.org/ontology/formationDate> ?date.
FILTER(STR(?date) = "2009-02-15")
}
which is also some kind of strange as I would assume the lexical form is
just "2009-02-15+02:00" .
Is there anything I'm doing wrong?
Kind regards,
Lorenz
--
Lorenz Bühmann
AKSW group, University of Leipzig
Group: http://aksw.org - semantic web research center
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