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[protege-owl] Tutorial for using SPARQL with OWL.

Olivier Dameron olivier.dameron at univ-rennes1.fr
Wed Sep 6 11:10:54 PDT 2006


On Wed, 06 Sep 2006 10:53:04 -0700, Holger Knublauch
<holger at knublauch.com> wrote:

> 
> 
> Massimo Coletti wrote:
> > Gerhard Austaller ha scritto:
> >>  
> >> problems that i can't figure aout how to solve. E.g. I try to get
> >> all individuals that are instances of a particular class including 
> >> individuals of subclasses of that class... Any hint?
> >>
> >>   
> > this is not possible in SPARQL, as the language have only notion
> > about asserted triples.
> 
> This is not exactly correct.  The SPARQL language itself doesn't care 
> whether a triple is inferred or asserted as long as the query graph 
> provides it.  For example, you can easily do SPARQL queries on top of
> a Jena inference graph.  But this is not possible in Protege.

Gerhard's question does not mention asserted vs. inferred.
I took it as a question about retrieving the "indirect" instances of a
class, i.e. the instances of some subclass of a class, no matter if the
subclass is asserted or infered.

Again, I don't think that this is possible because sparql is not aware
of the rdfs semantics (hence sparql is not aware of owl's semantics).
sparql doesn't understand the subclass assertions (which are processed
as any assertion) and it doesn't understand that rdfs:subClassOf is
transitive, which is also a problem in the case proposed by Gerhard. 

Other rdf query languages are aware of the rdfs semantics (e.g. SeRQL).
Therefore, the fact that Gerhard's wish is impossible is not a
limitation of Protege but only of sparql. Holger's remark is
perfectly correct, but gives the impression that the problem is Protege
whereas it is sparql (I think).

Olivier



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