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Re: [SKOS] the return of transitive and subproperty (was Re: SKOS comment: change of namespace (ISSUE-117))

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Thu, 31 Jul 2008 15:31:55 +0200
Message-ID: <4891BECB.2050704@mondeca.com>
To: Stephen Bounds <km@bounds.net.au>, SKOS <public-esw-thes@w3.org>

Stephen

Your argument makes sense of course. Some remarks, nevertheless, still 
in defense of my proposal

Stephen Bounds a écrit :
>
> One other observation which may or may not be accurate from the point 
> of view of the broader SKOS community.
>
> I've always seen SKOS as being primarily a tool for vocabulary 
> representation, *not* as a universal semantic reasoning tool.
>
> In other words, the goal of SKOS is to to accurately represent a 
> thesaurus-like hierarchy in an easily understood manner using a common 
> XML dialect.
>
> So I think having to do something like this:
>
> > 1. Declare only the direct broader assertions
> > 3. Compute the transitive closure of broader
> > 4. Compute the minimalBroader for each concept
> > 5. Check if 4. matches 1.
>
> just to establish a parent-child relationship between nodes in the 
> hierarchy greatly compromises the effectiveness of SKOS as a simple, 
> expressive, declarative language.
Actually, you don'*have* to do that. Most of the time, you can take it 
for granted that the asserted broader *are* the minimal broader. So 
simple applications can rely on this simple heuristic. Only direct 
broader being asserted, your application can handle this in a very basic 
way, without applying transitivity, and you have the same results as in 
the current semantics (broader = minimal broader).
You'll have to go through computing if you want to check vocabulary 
consistency, apply semantic extension, whatever.
>
> At the moment in SKOS, I can establish the parents and children of a 
> node by doing a simple XPath test on <skos:broader> and 
> <skos:narrower>.  I don't want to lose that by reverting 
> <skos:broader> back to a transitive property.
You still can do that in most cases, if you don't compute the transitive 
closure. Just take what is asserted ...

Bernard


-- 

*Bernard Vatant
*Knowledge Engineering
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Received on Thursday, 31 July 2008 13:32:37 GMT

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