There is a complication to the earlier solution, which will also get
bnodes (i.e. unnamed resources). For example if a class has a
restriction it won't be seen as a "root" class. To correct that,
filter out unnamed classes (I also changed the variable names to be
less confusing):
CONSTRUCT
{ ?cls rdfs:subClassOf owl:Thing .
}
WHERE
{ ?cls a owl:Class .
OPTIONAL {?cls rdfs:subClassOf ?superClass .
FILTER isIRI(?superClass)}.
FILTER (!bound(?superClass)) .
}
Another solution would be to create a SPIN function that returns a
true for all named classes:
ASK WHERE {
?arg1 rdfs:subClassOf ?superClass .
FILTER isIRI(?superClass) .
}
This can be used in a query to filter for all unnamed superclasses:
CONSTRUCT
{ ?cls rdfs:subClassOf owl:Thing .
}WHERE
{ ?cls a owl:Class
FILTER isIRI(?cls)
FILTER (!:hasNamedSuperClass(?cls))
}
This also outlines a useful idiom. The query calls hasNamedSuperClass
() for each matching resource. In effect, this is a way to do a "for
each" on a query (defined as a SPIN function). I.e. "for each
matching resource, call a query, passing the resource as an argument".
-- Scott
On Jul 2, 9:14 am, Scott Henninger <[email protected]> wrote:
> To determine if a class does not have a named superclass, you could
> use the SPARQL idiom for negation:
>
> CONSTRUCT
> { ?cls ?cls rdfs:subClassOf owl:Thing . owl:Thing .}
>
> WHERE
> { ?cls a owl:Class .
> OPTIONAL {?cls rdfs:subClassOf ?subc .} .
> FILTER (!bound(?subc)) .
>
> }
>
> If you do this in a SPARQLMotion script, import the RDF from the
> ontology you need to modify, apply the above construct query, then
> write to a file.
>
> -- Scott
>
> On Jun 30, 3:18 pm, J-MAN <[email protected]> wrote:
>
> > Thanks Holger, thats very helpful.
>
> > Is there an easy way (sparql query) to determine if a class does not
> > have a named superclass?
>
> > -J
>
> > On Jun 30, 3:51 pm, Holger Knublauch <[email protected]> wrote:
>
> > > Hi J,
>
> > > TopBraid does some background inferencing to infer extra superclass
> > > triples. This makes sure that any class has at least one named
> > > superclass, so that it can be reached from a tree traversal. You would
> > > need to either re-implement this logic yourself, or activate
> > > inferencing on sesame, or simply include the inference graph when you
> > > export the TBC to Sesame. Making matters a bit more complicating, the
> > > triple
>
> > > owl:Thing rdfs:subClassOf rdfs:Resource
>
> > > has been added by TopBraid into its system triples model, which is
> > > also imported by any project but cannot easily be exported as well.
> > > So, in this case I would recommend to replicate this same triple in
> > > your own file before exporting to Sesame, from the form of owl:Thing.
>
> > > Regards,
> > > Holger
>
> > > On Jun 30, 2009, at 12:39 PM, J-MAN wrote:
>
> > > > We are using TopBraid to build ontologies and data for our
> > > > application. We then move the data & onts to our sesame knowledge
> > > > store.
>
> > > > Our RDF works fine inside topbraid composer, but when we move it into
> > > > our sesame store, we are having problems because owl:Thing is not
> > > > being inferred as the base class.
>
> > > > How do you infer a class is a direct subclass of owl:Thing? Without
> > > > specifically asserting it?
>
> > > > Any suggestions?
>
> > > > Thanks
>
> > > > -J
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