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ISSUE-164: Extension vs mapping (SKOS Primer)

From: SWD Issue Tracker <dean+cgi@w3.org>
Date: Sat, 4 Oct 2008 14:21:34 +0000 (GMT)
To: public-swd-wg@w3.org,public-rdf-in-xhtml-tf@w3.org
Message-Id: <20081004142134.DD5A96B62C@tibor.w3.org>

ISSUE-164: Extension vs mapping (SKOS Primer)


Raised by: Antoine Isaac
On product: SKOS

Raised by Doug Tudhope in [1]

Open world discussion and extension vs mapping in 3.1 and 3.2

I’m a little concerned about the relative emphasis apparently given to extension
vs mapping. The primer might be read as suggesting that the default way of
connecting two KOS is via extension or direct linking, which I think would be
inappropriate. While there are good cases for (third party) extending a KOS (eg
by including local extensions), the wording in the intro to section 3 is perhaps
a little enthusiastic and might run the risk of not sufficiently recognizing the
potential problems of linking two different KOS. LIS experience has recognised
that any major KOS represents a particular world view and that joining two
different KOS in an effective manner is not necessarily straight forward. Hence
the emphasis on distinct mapping relationships.

Perhaps the editorial team could consider the appropriate order of the linking
and mapping sections, whether more discussion on the rationale for mapping could
be included, and whether some more guidance might be given on when to link and
when to map.

The linking example in section 3.1 brings up a currently somewhat problematic issue.
A new concept scheme can re-use existing concepts using the skos:inScheme
property. Consider the example below, where a reference concept scheme for
animals defines a concept for "cats":

However there is nothing to prevent a new developer attaching their own new
concept to someone else's existing SKOS scheme and thus changing the scheme (if
the links are followed). It would be bad practice but as far as I understand is
possible. (A slight modification of the example in 3.1 illustrates the point below.)

I appreciate this is integral to the open world model and in the long run, it
might be addressed by mechanisms of assigning provenance to RDF (sets of)
statements, development of trusted vocabulary registries, caution when importing
a SKOS vocabulary, etc. In the near future, I believe that the majority of
applications will be effectively closed world, in that they will create an
in-house index or database based on selected resources from the Web (including
linked data publications). Perhaps the SKOS primer might also address more
immediate concerns of how a vocabulary provider might make their vocabulary
available. Is it possible to say something on how KOS developers might publish a
vocabulary in SKOS, while asserting some practical form of ownership?


Eg A slight modification of the example in 3.1 if I understand it correctly
============= alt example (undesirable?)
ex1:referenceAnimalScheme rdf:type skos:ConceptScheme;
   dc:title "Reference list of animals"@en.
ex1:cats rdf:type skos:Concept;
   skos:prefLabel "cats"@en;
   skos:inScheme ex1:referenceAnimalScheme.

The creator of another concept scheme devoted to cat descriptions can freely
include the reference ex2:abyssinian concept in AN EXISTING scheme, and then
reference it as follows:

ex2:catScheme rdf:type skos:ConceptScheme;
   dc:title "The Complete Cat Thesaurus"@en.

ex1:cats skos:inScheme ex2:catScheme.

ex2:abyssinian rdf:type skos:Concept;
   skos:prefLabel "Abyssinian Cats"@en;
   skos:broader ex1:cats;
   skos:inScheme ex1:referenceAnimalScheme.
Received on Saturday, 4 October 2008 14:22:13 UTC

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