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RE: same as relation

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Thu, 15 Dec 2005 12:43:56 +0100
To: "Luis Bermudez" <bermudez@mbari.org>, <public-esw-thes@w3.org>
Message-ID: <GOEIKOOAMJONEFCANOKCKEHHHHAA.bernard.vatant@mondeca.com>


Hello Luis

> If I have two concepts from two different thesaurus, what is the
> recommended approach to say that they are both the same concept ?

Logical answer : if you have two concepts, they are not the same - otherwise you would
have one concept.

Elusive answer : depends on what you mean by "same", and what you mean by "concept" :))

Developed answer : this is IMHO *the* most difficult issue to solve for the next steps of
the Semantic Web (see [1] entirely dedicated to this).

Use case 1 : You have not yet assigned URIs in any of the thesauri, you are in the process
to migrate them to SKOS, and you have the power to assign URIs for both : then use the
same URI to identify the concept in the two thesauri. You have a single resource, and in
fact a single concept, with possible different descriptions in each thesaurus. This opens
questions about consistency of those two descriptions.

Use case 2 : You have not yet assigned URIs in the thesaurus A you manage, but have found
another thesaurus B where URIs are assigned, and your concept "foo" looks like the same as
the concept "bar" in thesaurus B. Two solutions come to mind:
- Use the URI of "bar" to identify "foo".
- Declare "foo" with a URI in your own namespace, and use owl:sameAs to declare identity.
a:foo		owl:sameAs	   b:bar
Those two solutions bear exactly the same semantics, which means everything you declare on
a:foo is valid for b:bar, and the other way round. They represent the same concept because
they are the same resource. Note that SKOS Guide does not recommend this kind of practice
at all. See http://www.w3.org/TR/2005/WD-swbp-skos-core-guide-20051102/#secidentity.

The above approaches ties the semantics of a:fooX to the semantics of b:bar. There is an
alternative approach I've been trying to push here [2] and there [3], and that maybe you
would be interested in. If you want to keep formal semantics independent, and that
same-ness of concept(s) represented by two or more resources is something more fundamental
that the declared formal semantics of those resources, you would like simply to declare
that a:foo and b:bar are two formal aspects of the same "a-semantic" concept, both
providing a specific and partial description of it. The basic assumption underlying this
approach is that there is no exhaustive formal description of a concept whatsoever, and
that different, independent descriptions might be orthogonal, complementary, and possibly
non-consistent.

Cheers

Bernard

[1] http://universimmedia.blogspot.com
[2] http://www.mondeca.com/lab/bernard/spek.rdf
[3] http://www.mondeca.com/lab/bernard/hubjects.pdf

----------------------------------
Bernard Vatant
Mondeca Knowledge Engineering
bernard.vatant@mondeca.com
(+33) 0871 488 459

http://www.mondeca.com
http://universimmedia.blogspot.com
----------------------------------

> -----Message d'origine-----
> De : public-esw-thes-request@w3.org
> [mailto:public-esw-thes-request@w3.org]De la part de Luis Bermudez
> Envoye : mercredi 14 decembre 2005 19:39
> A : public-esw-thes@w3.org
> Objet : same as relation
>
>
>
> Hi all,
>
> If I have two concepts from two different thesaurus, what is the
> recommended approach to say that they are both the same concept ?
>
> Thanks for your help,
>
> Luis
>
> ---------------------------------------
> Luis Bermudez Ph.D.
> Software Engineer
> MMI Liaison - http://marinemetadata.org
> bermudez@mbari.org
> Tel:  (831) 775-1929
> Monterey Bay Aquarium Research Institute
>
>
Received on Thursday, 15 December 2005 11:44:23 GMT

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