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Re: Differences between SKOS and ISO standards : transitivity

From: Leonard Will <L.Will@willpowerinfo.co.uk>
Date: Fri, 13 Feb 2009 21:27:50 +0000
Message-ID: <lj05iaGWXelJFAB6@mail.willpowerinfo.co.uk>
To: Simon Spero <ses@unc.edu>
Cc: Barbara Tillett <btil@loc.gov>, "Martha M. Yee" <marthamyee@sbcglobal.net>, "Allyson Carlyle (work)" <acarlyle@u.washington.edu>, Jane Greenberg <janeg@email.unc.edu>, "public-esw-thes@w3.org" <public-esw-thes@w3.org>, public-swd-wg@w3.org

On Fri, 13 Feb 2009 at 15:40:49, Simon Spero <ses@unc.edu> wrote
>On Fri, Feb 13, 2009 at 11:47 AM, Leonard Will
>I realise that I was not quite rigorous in what I said about transitivity in
>> my message earlier today. To  clarify, as I understand them to be used in
>> the thesaurus community and in ISO standards:
>> The generic relationship BTG is transitive
>> The partitive relationship BTP is transitive
>> The generalised  relationship BT can not be assumed to be transitive,
>> because different occurrences of it may represent a mixture of the above
>> types.
>I don't believe that the last  statement is correct.   As Svenonius(2000,
>p.130) explains:
>Subject language terms differ *referentially* from words used in ordinary
>language. The former do not refer to objects in the real world or concepts
>in a mentalistic world but to subjects. As a name of a subject, the term *
>Butterflies* refers not to actual butterflies but rather to the set of all
>indexed documents about butterflies. In a natural language the extension, or
>extensional meaning, of a word is the class of entities denoted by that
>word, such as the class consisting of all butterflies. In a subject language
>the extension of a term is the class of all documents about what the term
>denotes, such as all documents about butterflies.
>The BT relationship is thus transitive, because it operates over the domain
>of documents, not the domain of the items described by those documents.
>This is distinction is absolutely fundamental to understanding any formal
>model of controlled vocabularies and subject analysis.

I'm not convinced of this, I'm afraid. My understanding of the 
relationships in a thesaurus are that they are between the concepts 
represented there, and that we do not introduce an additional "is_about" 
relationship. This would seem to me to make the relationships much less 
distinct and potentially ambiguous.

>The inference rule that is in dispute is this one:
>A BT B, B BT C  |= A BT C
>This can be read saying "If all documents about A are also about B, and all
>documents about B are also about C, all documents about A are also about

Saying that "all books about ornithology are also about birds" is not 
the same thing as saying that there is a hierarchical relationship 
between ornithology and birds. There cannot be, because these concepts 
are in different fundamental categories (fundamental facets): one is in 
the "disciplines" facet and the other is in the "living things" facet.

>An S2000 Steering Wheel may be part of a Honda S2000, a Honda S2000 may be a
>type of car and a Car may be a type of Vehicle.

This example does not encounter this problem because all the concepts 
are from an "objects" facet, but the "is_about" relationship does not 
require this. It seems to me that the "is_about" relationship is an 
indicator of an associative relationship, not a hierarchical one. To 
take some examples from BS8723-2:2005, all books about herbicides are 
about plants; all books about toxicity are about poisons; all books 
about bereavement are about death [all the examples are not so gloomy!]. 
In none of these cases is there a hierarchical relationship between the 
concepts concerned - it is RT/RT.

I might add that I have done quite a lot of work in museum 
documentation, where the concepts do relate to actual butterflies or 
cars, but I don't think that the principle is different. The "is_about" 
relationship doesn't arise until we create links between the concepts in 
a thesaurus and the objects or documents that form the resources which 
we are indexing.

Willpower Information     (Partners: Dr Leonard D Will, Sheena E Will)
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Received on Friday, 13 February 2009 21:38:44 UTC

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