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Re: [SKOS]: [ISSUE 44] BroaderNarrowerSemantics

From: Antoine Isaac <aisaac@few.vu.nl>
Date: Mon, 26 Nov 2007 19:09:00 +0100
Message-ID: <474B0BBC.5040805@few.vu.nl>
To: "Reul, Q. H." <q.reul@abdn.ac.uk>
CC: public-swd-wg@w3.org, public-esw-thes@w3.org, Alistair Miles <a.j.miles@rl.ac.uk>

Hello Quentin, Alistair

The way I would treat "transitive broader" would be to
1. create a specialization of skos:broader (let's say, my:transitiveBroader)
2. declare it transitive (my:transitiveBroader rdf:type 
owl:TransitiveProperty)

This way, for the concepts involved in transitiveBroader statements, 
there will be some "locally transitive" broader.
If we have (ex:A,my:transitiveBroader,ex:B), 
(ex:B,my:transitiveBroader,ex:C) then we'll have 
(ex:A,my:transitiveBroader,ex:C) and hence (ex:A,skos:broader,ex:C)

Notice that in my mind this is very different from interpreting 
skos:broader as transitive, which would be skos:broader rdf:type 
owl:TransitiveProperty
And notice also that I *really object* to saying that, as Alistair 
writes it in the reference [1]

> Interpreting skos:broader as a Transitive Property would be consistent 
> with the SKOS semantics. Alternatively, interpreting skos:broader as 
> an Intransitive Property would also be consistent with the SKOS semantics.

If we have one case somewhere where skos:broader is not transitive, then 
*nobody on semantic web can assert that it is transitive*. Just consider 
the following case:
- John has a thesaurus for which broader is not transitive
- Mary has a thesaurus for which broader is transitive and, 
"interpreting skos:braoder as transitive", puts the infamous triple 
skos:broader rdf:type owl:TransitiveProperty in here knowledge base.
Then whenever a Semantic Web tool loads Mary's knowledge base at the 
same time as John's one, it would propagate unintended skos:broader 
statements (between the concepts of John's thesaurus)
With respect to this kind of problem, only the "locally transitive" 
specialization pattern I've proposed is safe.

Cheers,

Antoine

[1] http://www.w3.org/2006/07/SWD/wiki/SKOS/Reference

> Hi all,
>
> I think [ISSUE 44] might have been resolved at the f2f in Amsterdam a
> few months ago as I think to remember that we would allow people to use
> skos:broader/skos:narrower as both transitive and intransitive.
>
> However, I believe that these semantic relations should be made
> transitive. For each skos:ConceptScheme, there might have one or more
> top concept and there might have several subconcepts available for each
> of them. 
>
> Example:
> skos:ConceptScheme W
> W skos:hasTopConcept X
> X skos:narrower Y
> Y skos:narrower Z
>
> The user might want to know that Z skos:broader X. Or would simple graph
> operation be enough to find all the sub- or super- concepts?
>
> Furthermore, we have defined a skos:Concept rdf:type owl:Class and hence
> skos:broader and skos:narrower could be used to describe owl:Class in
> ontologies. I'm not sure that we want skos:semanticRelation to be
> applied between owl:Class.
>
> I'm sorry if any of these issues have already been covered.
>
> Regards,
>   
> Quentin
>
> [ISSUE 44] http://www.w3.org/2006/07/SWD/track/issues/44
>
> ******************************************
> * Quentin H. Reul                        *
> * PhD Research Student                   *
> * Department of Computing Science        *
> * University of Aberdeen, King's College *
> * Room 238 in the Meston Building        *
> * ABERDEEN AB24 3UE                      *
> * Phone: +44 (0)1224 27 4485             *
> * http://www.csd.abdn.ac.uk/~qreul       *
> ******************************************
>
>
>
>
>   
Received on Monday, 26 November 2007 18:13:01 UTC

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