Greetings,
I noticed a discrepancy between my expectations and the results I get from a
few SPARQL queries on DBPedia:
Querying DBPedia for a listing of all television stations returns no
results:
SELECT ?x
WHERE {
{ ?x rdf:type <http://dbpedia.org/class/yago/TelevisionStation104406350> }
}
However if I specify to include instances of subclasses one inheritance
level down, results do appear:
SELECT ?station ?subclass
WHERE {
?station rdf:type ?subclass.
?subclass rdfs:subClassOf
<http://dbpedia.org/class/yago/TelevisionStation104406350>
} LIMIT 100
I expected the first query to return the results of the second (with
additionally all the transitive subclasses), and I just wanted to ask on
this list, is this an incorrect expectation? Shouldn't the query engine
automatically infer that instances of subclasses are also instances of
superclasses and include those in the result? I thought this kind of useful
inferencing was one thing that gave SPARQL it's shine!
I have pointed out this issue in this blog
post<http://curransoft.com/code/2011/05/querying-dbpedia-for-tv-stations/>.
Thanks
for your time!
Best regards,
Curran Kelleher
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