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RE: SKOS ISSUE-39: clarification?

From: Emma McCulloch <e.mcculloch@strath.ac.uk>
Date: Tue, 4 Dec 2007 09:59:51 -0000
Message-ID: <2C50F05E7BE301499FDE5A2820E4CFE0627C36@BE-SCAM2.ds.strath.ac.uk>
To: "Antoine Isaac" <aisaac@few.vu.nl>, "SKOS" <public-esw-thes@w3.org>
Cc: "SWD WG" <public-swd-wg@w3.org>

Hi Antoine,
Many thanks for your reply; it has definitely cleared a few things up for me.
I totally agree with the proposed deprecation of major and minorMatch. We found it particulary difficult to come up with an example of what might constitute a minorMatch and the division at the 50% point was extremely difficult to gague, as you say. I also agree that overlappingMatch is a valuable mapping type and will be far more straightforward to apply. I think we're finding the application of the mapping vocab quite difficult in HILT generally, since SKOS is geared towards equivalence between indexed resources, whereas we are looking purely at thesaurus terms with no attachment to actual resources.
The platypus/egg example has made things clearer (as has your France/War example) but I believe there will be instances where the distinction between related and overlapping might be more blurred. I'm not absolutely convinced that they are sufficiently distinct if both are to be used in inter thesaurus mapping. I'll try to find some examples of this in our ongoing mapping work.
Thanks again, your response is much appreciated,


From: public-esw-thes-request@w3.org on behalf of Antoine Isaac
Sent: Mon 03/12/2007 21:45
To: SKOS; Emma McCulloch
Subject: Re: SKOS ISSUE-39: clarification?

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

> 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,


[2] http://www.w3.org/2006/07/SWD/track/issues/40
Received on Tuesday, 4 December 2007 10:03:32 GMT

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