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Re: SKOS ISSUE-39: clarification?

From: Antoine Isaac <aisaac@few.vu.nl>
Date: Mon, 03 Dec 2007 22:45:02 +0100
Message-ID: <475478DE.1090205@few.vu.nl>
To: SKOS <public-esw-thes@w3.org>, e.mcculloch@strath.ac.uk
CC: SWD WG <public-swd-wg@w3.org>

Dear Emma,

I'm very glad to have some comments by someone from HILT! I will try to 
answer your questions below:
>
>
> 1)       What is the status of this issue and proposal (ISSUE-39)?
>

The issue states that there is a requirement for SKOS (i.e. conceptual 
mapping links) that is not dealt with in the current version of SKOS. 
And [1] is a proposal to tackle this issue, by having the SKOS namespace 
featuring some constructs devoted to mapping representation. Even if 
SKOS mapping (I'll keep the MVS you use for it) is around, it is not 
stable and has no official W3C status.
Notice that for the moment [1] has no official status either, it's just 
a proposal to be discussed. Your comments/questions are therefore highly 
welcome.

>
> 2)       ISSUE-39 states that Major/minorMatch are deprecated, along with
> classes AND, OR and NOT. It also 'transfers' skos:mappingRelation,
> skos:exactMatch; skos:broadMatch and skos:narrowMatch from the MVS 
> into the
> standard SKOS vocabulary. Does this mean that the MVS will no longer 
> be used
> if this proposal is accepted?
>

Yes, the current proposal states that MVS would not exist as such any 
more. Some of its elements would be purely deprecated (major/minorMatch) 
while some other would be technically deprecated but in practice moved 
to the 'official' SKOS namespace. the latter case would be true for the 
mappingRelations, but also perhaps for AND/OR/NOT. The resolution for 
the last elements would wait till a resolution for another issue, 
ISSUE-40 [2]
Notice again that this is a proposal, which can be adjusted. For 
example, even if people agree on removing major/minorMatch, there could 
be a consensus on keeping the official mapping vocabulary in the same 
separate namespace that is used now (http://www.w3.org/2004/02/skos/mapping)

>
> 3)       skos:relatedMatch and skos:overlappingMatch are introduced: could
> you please provide a definition of relatedMatch (assuming this is for
> inter-thesaurus mapping) and perhaps an example? I'm not clear of the
> distinction between this and overlappingMatch, at a practical level.
>

Before answering this question: is the platypus/egg example in [1] not 
clear enough? If yes, please say so, and I'll try to find another one...

That being said, the difference between relatedMatch and 
overlappingMatch is not 100% obvious even to me.
The main motivation is that the previous SKOS mapping specification was 
assuming a quite 'mechanical', extensional approach to partial mappings. 
minor/majorMatch were defined on the basis that resources were described 
by both mapped concepts.
If I wanted to remove minor/majorMatch (because I find the 50% criterion 
too much arbitrary), I had to find something with the same kind of 
criterion to replace them (because I thought there was some point in 
representing this "overlapping extensions" situations). So 
overlappingMatch is defined as a relation that holds when there is a set 
of documents potentially described by the two concepts at the same time.
The problem is that this does not render the associative "related" link 
between terms from a thesaurus. Imagine two concepts, "France" and 
"War", coming from two thesauri. In a library, there will be an overlap 
between the sets of books indexed by the two concepts. Yet, I dare not 
imagine that there would be a "related" link between the two concepts, 
if they stood withing one single thesaurus. If a searcher is interested 
in resources about "France", you will not generally try to point him to 
resources about War. In my opinion, this is a case where you would have 
an overlapingMatch but no relatedMatch.
Does this make enough sense? (please do not hesitate to say if you are 
not fully convinced)

>
> 4)       The first version of ISSUE-39 proposed to introduce
> skos:equivalentConcept as a replacement for skosm:exactMatch - has 
> this idea
> now been dropped?
>

Yes. The first proposal tried to deprecate the current MVS as much as 
possible, and to have it replaced it by the exsiting SKOS semantic 
relations (broader, related, narrower, but there is no equivalence link 
until now in this part of SKOS). Given that this proposal has not been 
very popular, I took the inverse stance, which is to keep mapping links 
distinct from semantic relations. I thought that in this case it would 
be better to stay as close as possible to the MVS elements.

Best regards,

Antoine

[1] 
http://www.w3.org/2006/07/SWD/wiki/SkosDesign/ConceptualMapping/ProposalTwo
[2] http://www.w3.org/2006/07/SWD/track/issues/40
Received on Monday, 3 December 2007 21:47:05 GMT

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