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

From: Stephen Bounds <km@bounds.net.au>
Date: Thu, 31 Jul 2008 23:43:30 +1000
Message-ID: <4891C182.8050501@bounds.net.au>
To: Simon Spero <ses@unc.edu>
CC: Antoine Isaac <Antoine.Isaac@KB.nl>, SKOS <public-esw-thes@w3.org>

G'day Simon,

I understand what you're saying, but that is not really my objection.

If someone wants to implement a polyhierarchical thesaurus, then this 
kind of structure is quite common:

        Animals
           |
           |
         Birds
          |  \
          |   \
          |   Australian Birds
          |    |       |
          |    |       |
         Cockatoos    Emus

If <skos:broader> is non-transitive, then there is a single, unambiguous 
way to represent this hierarchy.

But if <skos:broader> is transitive, then asserting

   Cockatoos skos:broader Birds

does *not* tell us whether the author intends a direct link between 
Cockatoos and Birds in the hierarchy.

Now, from a semantic reasoning point of view, the presence or absence of 
this parent-child link is irrelevant:  'Birds' is broader than 
'Cockatoos' in either case.

But it's *not* irrelevant in terms of how the thesaurus gets presented 
to an end-user, and that's precisely my point.

Regards,

-- Stephen.

Simon Spero wrote:
> Stephen-
> If you aren't using a reasoner, then you don't need to start doing so to 
> introspect and undo the effects of using... a reasoner.
> 
> If you are working with an rdf suite like Redland, and don't hook it up 
> to an inference engine, you just get the direct assertions.
> 
> You don't have to draw every conclusion entailed by ones knowledge base; 
> the black lump lying on my feet is ki-chan. I do not need to access the 
> fact that he is a eukaryote to know he's being friendly because he wants 
> second breakfast; I only need to know that he's a cat.
> 
> It's when you *publish* data that you need to take care not to use 
> hierarchical relations in cases where the link is not truly hierarchic.
> 
> Simon
> 
> Sent from my iPhone
> 
> On Jul 31, 2008, at 5:22 AM, Stephen Bounds <km@bounds.net.au> wrote:
> 
>>
>> Hi Antoine,
>>
>> Yes, I am in favour of the current SKOS version.
>>
>> I strongly believe SKOS is most likely to see broad uptake if people 
>> *don't* need SPARQL or some other RDF query dialect to do useful 
>> things with it.
>>
>> Cheers,
>>
>> -- Stephen.
>>
Received on Thursday, 31 July 2008 13:44:18 GMT

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