Re: SKOS and MeSH qualifiers

In message 
<D53793AA582576458786FBE27899DB18EA3794@OAEXCH2SERVER.oa.oclc.org> on 
Fri, 8 Jul 2005, "Houghton,Andrew" <houghtoa@oclc.org> wrote
>This issue comes up in controlled vocabularies like LCSH which uses 
>subdivisions, e.g. field tags 18X, and some thesauri that allow common 
>form type subdivisions.  I agree that it is not immediately evident as 
>to how you should represent these parts of the vocabulary in SKOS.  The 
>collections idea is interesting, but I'm not sure that's what the 
>intent was. I'd like to hear Miles' thoughts on how to describe them in 
>SKOS since I'm currently working with LC Radio genre that has common 
>form subdivisions.

Terms with subdivisions or MeSH-type "qualifiers" are really 
pre-coordinated strings made up of two or more thesaurus concepts. The 
syntax and the allowed combinations for these strings would normally be 
incorporated in rules for pre-coordination which are separate from the 
elementary concepts and their labels in the thesaurus itself.

Work is being done at OCLC to recognise this by decomposing LCSH strings 
into their constituent facets, which can then be used separately in 
post-coordinate indexing applications. See
<http://www.oclc.org/research/projects/fast/default.htm>

Essentially for LCSH you can separate out subdivisions into separate 
facets for "subjects", "places", "forms", "time" and "names" (i.e. 
people and organisations), which can then be combined into strings 
according to a prescribed citation order of facets.

The facets appropriate for MeSH "qualifiers" are not distinguished, but 
can be identified as, for example

disciplines:
----------------
Anatomy & Histology
Chemistry
Cytology
Economics
Education
Embryology
Enzymology
Epidemiology
Ethnology
Etiology
Genetics
etc.

actions (operations and processes):
-----------------------------------------------------
Administration & Dosage
Adverse Effects
Analysis
Biosynthesis
Diagnosis
Diagnostic Use
Diet Therapy
Drug Effects
Drug Therapy
etc.

materials:
--------------
Agonists
Blood
Urine

and so on.

I would suggest that all concepts such as these should be recorded 
independently as separate entries in the thesaurus and be available for 
assignment to documents in addition to other "subject" terms.

The rules for building pre-coordinated strings of terms, and the 
restrictions on possible combinations which are imposed by some schemes 
such as LCSH and MeSH, do not normally form part of a thesaurus 
structure. It is best if these rules can be generalised as far as 
possible, e.g. by specifying a standard citation order for facets, but 
for historical reasons some schemes have rules which are specific to 
particular terms. I am not sufficiently familiar with the RDF encoding 
schemes to be able to specify how and where such rules should be stored. 
They are not part of a thesaurus as such, but it would be necessary to 
provide for them if the SKOS scheme is to be extended to cover 
pre-coordinated subject indexing and classification schemes.

Leonard


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Received on Monday, 11 July 2005 09:43:29 UTC