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Re: ISSUE-186: Last Call Comment: Mappings

From: Stella Dextre Clarke <stella@lukehouse.org>
Date: Wed, 22 Oct 2008 11:17:59 +0100
Message-ID: <48FEFDD7.90801@lukehouse.org>
To: Alistair Miles <alistair.miles@zoo.ox.ac.uk>
CC: public-swd-wg@w3.org, public-esw-thes@w3.org

This is just to endorse Alistair's comments on ISO 5964 and BS8723-4, 
which I think are good interpretations. (Although his mention of 
BS8723-5 is probably a typo). A couple of things to clarify/add:

1. The descriptions of "exact" "partial" and "inexact" equivalence in 
ISO 5964 are not meant to specify three distinct relationship types in a 
multilingual thesaurus; they are observations on what one encounters in 
natural language during the process of deciding what terms/concepts to 
include in a multilingual thesaurus, and which equivalence relationships 
to establish in it. And ISO 5964 does not deal at all with mappings 
between thesauri.

2. Re the unwisdom in BS8723-4 of juxtaposing construction of a 
multilingual thesaurus with building mappings between thesauri, the 
committee developing ISO 25964 has taken much the same view. ISO 25964 
will be the number of the standard which will update ISO 5964 and ISO 
2788. It will be based on BS 8723, but the content will be rearranged. 
All the material about building a thesaurus, whether monolingual or 
multilingual, will be in Part 1 of ISO 25964. All the material about 
mappings between thesauri will be in Part 2. We hope that will resolve 
any current confusion.

Stella Dextre Clarke
Project Leader, ISO NP 25964

Stella Dextre Clarke
Information Consultant
Luke House, West Hendred, Wantage, OX12 8RR, UK
Tel: 01235-833-298
Fax: 01235-863-298

Alistair Miles wrote:
> Hi all,
> At yesterday's telecon Guus took an action to respond to this
> comment. Here are a few notes of my own based on comment I made
> yesterday.
> On Wed, Oct 08, 2008 at 10:09:25AM +0000, SWD Issue Tracker wrote:
>> ISSUE-186: Last Call Comment: Mappings
>> http://www.w3.org/2006/07/SWD/track/issues/186
>> Raised by: Sean Bechhofer
>> On product: SKOS
>> Raised by Michael Panzer [1]:
>> 6. Mappings
>> -----------
>> The problem of restricting SKOS to one-to-one mappings has already been
>> raised as ISSUE-131. We share the concerns expressed there.
>> We also see potential problems in deriving the mapping relations
>> skos:broadMatch and skos:narrowMatch from skos:broader and
>> skos:narrower. In ISO standard and current practices many multilingual
>> thesauri did not use broader or narrower to indicate the mapping
>> relations. SKOS should revisit those standards and follow the current
>> standards' development to make sure SKOS is consistent in representing
>> the indicators used by standards (and the thesauri following those
>> standards) for so many years.  
> The SKOS mapping properties have their roots in ISO 5964 and have been
> informed more recently by BS 8723 part 4.
> I don't have ISO 5964 to hand so I may not quote precisely from it
> here, hopefully others can correct me if I make any glaring errors.
> ISO 5964 introduced the notions of exact, inexact and partial
> correspondance between thesaurus descriptors. These provided
> inspiration for the SWAD-Europe report on inter-thesaurus mapping,
> which first described the use of the SKOS Mapping RDF schema [1].
> Note in particular that the "partial" correspondance as described in
> ISO 5964 indicated that the meaning of one descriptor *either*
> subsumes *or* is subsumed by the meaning of the other. Hence [1]
> refined the notion of a partial mapping to provide broad and narrow
> mapping properties, which are clearly more useful than the ambiguous
> "partial". We felt this was consistent with the intention of ISO 5964
> (see also note [2]).
> BS 8723 part 4 ("interoperability between vocabularies") provides a
> clear (IMO) discussion of mapping between extant vocabularies. It
> illustrates the use of standard hierarchical and associative
> relationships (BT, NT and RT), in addition to an equivalence (EQ)
> relationship, to assert mappings between vocabularies, in what they
> call "differentiated mappings". These directly correspond to the
> skos:broadMatch, skos:narrowMatch, skos:relatedMatch and
> skos:exactMatch properties. (See also note [3].)
> We realise that "undifferentiated mappings" (where the nature of the
> correspondance is not specified) may represent the majority of real
> world mapping data. However, "differentiated mappings" are also an
> important resource, and are being constructed at scale e.g. by FAO.
> Hence the current design for SKOS is based on a perceived consensus
> for mapping between vocabularies, which is to ground the different
> types of mapping relationship in the notions of hierarchical and
> associative relationships, and we believe that this consensus is
> consistent with existing standards.
> Cheers,
> Alistair.
> [1] http://www.w3.org/2001/sw/Europe/reports/thes/8.4/ 
> [2] IMO ISO 5964 requires careful interpretation. From previous
> readings, I understood that ISO 5964 is primarily aimed at describing
> the *process* of constructing a single multilingual thesaurus, *not*
> on mapping between extant monolingual thesauri in either the same or
> different languages. The notions of "exact", "inexact" and "partial"
> are used to describe the types of correspondance that can be
> encountered between different language components *during the process
> of constructing a multilingual thesaurus*, with the implication being
> that anything other than an exact correspondance must usually be more
> closely aligned before the thesaurus is finally published.
> [3] Although the main body of BS 8723-4 discusses mapping between
> vocabularies (sections 5-8), where the assumption is that
> modifications to each vocabulary cannot be made to improve the
> alignment, BS8723-5 also discusses the process of constructing a
> single multilingual thesaurus (section 9), where changes can be made
> to each language component to improve the overall alignment of the
> thesaurus. IMO section 9, whilst valuable, is out of place in
> BS8723-4, because the process of constructing a single multilingual
> thesaurus (where language components can be modified to improve
> alignment) is different from the process of mapping between extant
> thesauri (where mappings have to describe aligment as-is), and would
> be better treated in a separate document.
Received on Wednesday, 22 October 2008 10:27:56 UTC

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