Re: SKOS without OWL

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. Transitivity only 
allows to declare only the direct children to construct a tree. Indeed 
the application rules when using the hierarchy may vary, like limiting 
the part of tree used for retrieval, display, navigation. But even if 
you limit for practical resaons your genealogy to the tenth generation, 
it does not mean the previous generations are not your ancestors (even 
if you don't know them and don't care).
"Limited transitivity" is a strange concept making people say that to 
get there, you should not start from here. ;-)
> 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
> Maybe OWL is needed for subjectIndicators because of
> owl:InverseFunctionalProperty 
... assuming that subjectIndicator being an IFP is not a bug ... (see 
previous exchanges)

Bernard

-- 

*Bernard Vatant
*Knowledge Engineering
----------------------------------------------------
*Mondeca**
*3, cité Nollez 75018 Paris France
Web:    www.mondeca.com <http://www.mondeca.com>
----------------------------------------------------
Tel:       +33 (0) 871 488 459
Mail:     bernard.vatant@mondeca.com <mailto:bernard.vatant@mondeca.com>
Blog:    Leçons de Choses <http://mondeca.wordpress.com/>

Received on Tuesday, 14 November 2006 09:23:10 UTC