RE: SKOS without OWL

Bernard, Jakob
> 
> Jakob
> > 1. Transitivity
> >
> > skos:broader and skos:narrower are defined as transitive. In my
point of
> > view this is just an error of design in SKOS because if you
inference
> > the transitivity rule, your full tree of concepts gets expanded.
This is
> > not suitable for common retrieval tasks where you only want to
expand to
> > a certain depth (please correct me if I am wrong). Your application
> > needs to expand skos:broader and skos:narrower depending on rules
that
> > are independet from OWL anyway.
> >
> Well, yes and no. Seems to me that all hierarchies of index, thesauri,
> classification schemes ... are implicitly transitive. 

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.

> > 2. Symmetric and inverse properties
> >
> > If you get data in SKOS you should *always* normalize it by checking
and
> > adding inverse properties[*]. This could be done with SPARQL:
> >
> > PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
> > PREFIX owl:  <http://www.w3.org/2002/07/owl#>
> > CONSTRUCT    { ?x ?p1 ?y }
> > WHERE        { ?y ?p2 ?x. ?p1 owl:inverseOf ?p2 }
> >
> > For this action you don't have to know anything about OWL.
owl:inverseOf
> > is just a property that is identified by an URI.
> >
> Right

I agree that this does the trick, but still am really not convinced of
the interest of encoding these semantics (at the level of a
recommendation) in SPARQL queries. OWL specification is by far more
interoperable (where do you publish this query? How do you link it to
the SKOS properties which are inverse of each other?) and even in this
case, clearer (why would users like to deal with all these variables?).
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.

Antoine

Received on Tuesday, 14 November 2006 11:36:05 UTC