RE: SKOS without OWL

Jakob,

> >
> > I encountered cases where it is not. Still I believe that it could
be
> > useful to have a version where this property is not transitive, and
an
> > extension offering a transitive version (superproperty, or different
> > 'dialect', as for OWL). But this should be discussed, of course.
> 
> Good idea! In [1] skos:borader, skos:narrower and skos:related are
> subproperties of skos:semanticRelation. There should be two new
> properties in between:
> 
> skos:narrower  rdfs:subPropertyOf  skos:descendant.
> skos:broader   rdfs:subPropertyOf  skos:ancestor.
> 
> with skos:ancestor and skos:descendant beeing transitive instead of
> skos:broader and skos:narrower. So if you do OWL reasoning you don't
> loose all the information which Concepts were *directly* related to
each
> other but you can also get the transitive closure with skos:descendant
> and skos:ancestor.
> 
> The same applies to skos:subject and the Subject Generality Rule. With
> inference you loose the possibility to rank result depending on
whether
> they are directly indexed with a concept or indirect with a concept
that
> is descendant of the concept you are searching for.
> 
> I'd propose two new properties skos:indexedWith and skos:indexes with:
> 
> skos:indexedWith  rdfs:subPropertyOf  skos:subject.
> skos:indexes      rdfs:subPropertyOf  skos:isSubjectOf.
> 

Something like that, yes. In line with previous experiment with the
Sesame RDFS engine (which coins a 'directSubClassOf'), I always thought
about names like 'directBroader' or 'directSubject'. But the pattern is
the same.
 
> Right - the SPARQL query is just an implementation, not the
> specification. I wanted to show that up to now you *cannot* use OWL
with
> inference (because transitivity will destroy information about
> hierarchical relations that is probably needed for retrieval) but you
> also don't have to use OWL because you can easily implement the
> reasoning yourself.
> 
> 
> > Of course I understand that the point in this solution is to avoid
using
> > an OWL reasoner, and therefore there is practical relevance.
However,
> > I'm really far from convinced that a SKOS recommendation should
advice
> > people to systematically - as you say it - emulate OWL reasoning by
> > systematically completing the data they have with SPARQL construct
> > queries.
> 
> The spec should define SKOS in a way that lets you use OWL reasoning
or
> implement the needed rules without OWL. To my impression [2] does this
> but as shown above there are new properties needed and rules to be
> changed.

Agreed for the "lets". But it should encourage people to specify their
specific extensions/interpretation using OWL, whenever this is possible.
Don't forget OWL is now the standard language for ontologies... This is
a situation quite similar to what SKOS situation would be. You can
represent your KOS using whatever complex construct is needed for it
(qualification etc.) but whenever you can link to SKOS classes and
properties, do it!

Cheers,

Antoine

Received on Wednesday, 15 November 2006 15:04:41 UTC