Pre or Post-Coordinate Indexing?

Most people think about what they want to search for and are willing to combine their concepts at the time of search. If you think of the way people search in Google, they put in the combination of terms they are thinking of; they are doing the coordination of terms. It is up to the search software to do the intersection of the terms for them and figure out the post-coordination.

In the current online environment, very seldom do we put together terms in a pre-coordinate fashion. That is one of the challenges in taking older classified lists – back-of-the-book indexes – and making them into a post-coordinate system.

Pre-coordination of terms is typical of traditional classification systems, and not of most modern taxonomies and thesauri. Classification systems often concatenate separate concepts into a string of terms. Natural language is not used.

I really think that most people search by typing in words as they think of them, so we need to support natural language in our systems. This is part of why Access Innovations uses post-coordination in the taxonomies and thesauri it creates.

In a post-coordinate system, a single concept is represented by a single term. We’re not combining 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.

Marjorie M.K. Hlava
President, Access Innovations

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