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RE: pre- and post- coordinate indexing

From: Aida Slavic <aida@acorweb.net>
Date: Wed, 19 Oct 2005 17:25:04 +0100
To: <public-esw-thes@w3.org>

>Can you give me an example of how syntax rules for pre-coordination are

Syntax rules for classification are what defined in citation order (each
classification system
has its own ... I think we mentioned before on this list e.g. PMEST -

Subject heading systems(LCSH, RAMEAU, RSWK, MESH etc.) work with "headings"
(simple or already precoordinated e.g.
'Ecosystem preservation' and subheadings that follows separated by -- e.g.

Ecosystem preservation--Central Africa--20th century--case study
Leather--trade--Italy--Middle Ages--bibliography

System like LCSH will offer a ready-made list of headings with their
specific topical subheadings (for instance heading Space
will have option of -- Exploration -- Travel ...)  and would allow for
further structuring adding
geographical and time subheadings or subheadings from so called 'floating
Even the rules for the most basic SH systems would regulate the exact
position of time, space and form
subheadings. LCSH, for instance have rule that subheadings of larger
geographical units should be added directly after
the heading (e.g. Leather -- Italy -- Trade and not Leather -- Trade --

>This answers another question I had which is: does the order of
coordination matter?

>In the example I used 'cut flowers + crop production' as the 'coordinated'
indexing term, used for the non-descriptor 'cut flower production', is this

I am not sure but I think that your example may not be valid for other
reasons than order of terms.
Subject heading system would normally allow topical subheading --Production
to be directly added to any number of items to specify the subject of
their production while 'Crop production' may be a heading on its own and
would be used
to index different things (e.g. documents on general issue of crop
In information retrieval this matters in a sense that 'cut flowers AND crop
production' may give different results from a search of
'Cut flowers -- production'. Again searching for 'cut flowers OR crop
production' may result with unmanageable recall

Generally speaking the order of terms matters only in a certain percentage
of the total retrieval situations. I.e.
pre-coordinated indexing will occasionally give better (more precise)
results than a simple post-coordinated
searching... One often has to think to find such an example:
- computers AND education (is this application of computers
in education or teaching how to use computers?) - in classification citation
order will determine the exact subject by putting a 'treated'
subject first and subject of treatment second....

(the same 'philosophy of history' and 'history of phylosophy')

I am not sure whether this answers your question

Received on Wednesday, 19 October 2005 16:25:17 UTC

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