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Re: faceted classification

From: Leonard Will <L.Will@willpowerinfo.co.uk>
Date: Mon, 22 Mar 2004 14:59:17 +0000
Message-ID: <eZ+UKjJF9vXAFAhc@willpowerinfo.co.uk>
To: "Miles, AJ (Alistair)" <A.J.Miles@rl.ac.uk>
Cc: "Douglas Tudhope (E-mail)" <dstudhope@glam.ac.uk>, "Stella Dextre Clarke (E-mail)" <SDClarke@lukehouse.demon.co.uk>, "'public-esw-thes@w3.org'" <public-esw-thes@w3.org>

In message
<350DC7048372D31197F200902773DF4C04944189@exchange11.rl.ac.uk> on Mon,
22 Mar 2004, "Miles, AJ (Alistair)" <A.J.Miles@rl.ac.uk> wrote
>Hi Doug, Leonard, Stella,
>I just read the article [1] that Doug forwarded.  I was wondering if you
>could help to me to clear something up.
>I have so far come across two meanings for 'faceted classification':
>(Sense 1)
>A set of things are 'classified' according to their properties.  For example
>(from [1]) a set of detergents are classified by 'brand name', 'form',
>'scent', 'agent', 'effect on agent' and 'special property'.  In this sense,
>each of these properties represents a 'facet' through which the set of
>instances can be viewed.
>(Sense 2)
>A set of 'concepts' are grouped according to their most primitive type.  For
>example, the concept 'marble' is placed in the 'materials' facet.  The
>concept 'insects' is placed in the 'organisms' facet.  In this sense, a
>'facet' is essentially a primitive class, and every member of a facet group
>is either an instance or a sub-class of that class.
>So my first question is: have I described these two senses accurately (or am
>I missing something)?


Congratulations on recognising at first reading an ambiguity that I've
been banging on about for years!

The terminology of faceted classification is indeed not well controlled.

Some people use the expression "subfacets" for your sense 1 and
"fundamental facets" for your sense 2, but I think that this is
confusing because they are indeed different, and not specific types of
some more general things called "facets".

The main need, as you point out, is to distinguish these two senses and
to use different names for them. The choice as to which should be given
the word "facets" is difficult, as there is warrant for either, but the
interpretation I have advocated, and which is in the draft British
Standard currently under preparation, is to use "facets" for your sense
2, i.e. "fundamental facets", sometimes called "fundamental categories".

For sense 1, an accepted terminology is to say that concepts are grouped
into "arrays" according to specified "characteristics of division". The
"characteristic of division" is shown in a node label, after the word
"by". These node labels are not descriptors, but explain the grouping of
concepts in the array that they introduce. You then have a hierarchy
such as the following which shows three arrays:

     <detergents by form>
     liquid detergents
     gel detergents
     powder detergents

     <detergents by scent>
     citrus scented detergents
        lemon scented detergents
        orange scented detergents
     pine scented detergents

     <detergents by brand name>
     Persil detergents
     Daz detergents
     Surf detergents

Note that in this case the arrays all list kinds of detergents. If you
wanted to separate out the properties from the detergents, you would
have distinct hierarchies such as

     citrus scents
        lemon scents
        orange scents

physical states

and these would belong to different [fundamental] facets.

The AAT puts "scents" (i.e. "odors") into an  "environmental concepts"
facet and "powders" into a "materials" facet under the node label
<materials by physical form>.

In this case these terms would come together with detergents only when
both descriptors were assigned to an item when that item was being

I hope other people agree with this description.


>My second question is: are there any other senses of 'faceted
>classification' worth considering?
>Finally: if my analysis is correct, these two senses describe quite
>different systems of organisation (*).  So would it be useful in the short
>term to come up with unambiguous names for these two meanings?  For example,
>we could refer to sense 1 as 'classification by description' and sense 2 as
>'primitive classification'.
>Please let me know what you think.
>(*) although sense 2 could be viewed as a special case of sense 1, in which
>concepts are classified according to the value of a 'primitive type'
>property - i.e. 'primitive type' represents a 'facet' in sense 1!
>[1] <http://www.miskatonic.org/library/facet-web-howto.html>
>Alistair Miles
>Research Associate
>CCLRC - Rutherford Appleton Laboratory
>Building R1 Room 1.60
>Fermi Avenue
>Oxfordshire OX11 0QX
>United Kingdom
>Email:        a.j.miles@rl.ac.uk
>Tel: +44 (0)1235 445440

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Received on Monday, 22 March 2004 10:02:23 UTC

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