Page 96 - DLIS405_INFORMATION_STORAGE_AND_RETRIEVAL

Unit 9: Trends in Indexing

In a post-coordinate system, a single concept is represented by a single term. We’re not combining Notes
two concepts, we are keeping them separate. That way we are able to do a large amount of automated
indexing. If we try to mine the text at the beginning, it is very system-intensive. So, we have taken
another path, by and large, for that.

Differentiate between Pre or Post-coordinate Indexing.

9.8 Pre-coordinate Indexing/Post-coordinate Indexing System

Purpose of all kinds of indexing is the retrieval of information. There are basically two types of retrieval
systems.

9.8.1 Pre-coordinate Indexing System

The kind of system in which coordination is done at the time of indexing is called pre-coordinate
indexing system. In this system documents or searched under the same terms which the indexer
originally assigned to them without any furthers manipulation of terms at the time of searching. It
means that whatever compound terms are used they are created at the time of indexing. Rather than
at the time of searching.

Co-relations are made during the indexing process and prior to use at the index,
it is also called pre-coordinate or pre-correlative indexing.

The subjects represented in pre-coordinate indexes are shown with the entire component concepts
coordinated. Thus, the entries in an index based upon pre-coordination are as complex as is necessary
to describe the subject. But complex or composite subjects demand a series of entries and terms in
order that they are described adequately.
An example:
• Chain indexing by S.R.Ranganathan
• PRESIS–Preserved context index system by derrick Austin
• POPSI–Postulate based Permuted Subject Indexing by G.Bhattacharya
• SLIC–Selective Listing In Combination by J.P.Sharp

Advantages:

1. Pre-coordinate indexes eliminate the need for sophisticated search logic. The use at the index
just looks under the terms that are expects to find the subject described. This is a direct
method of search with which users are well acquainted.
2. It requires no special features in their physical format. Almost all printed indexes reflecting
pre-coordinate indexing principles, are hard copy.
3. Its principles are applicable to a limited extent in on-line or off-line searched computer based
information retrieval systems.

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