Combined Thesaurus Tables

A combined thesaurus table combines the features of a classic thesaurus table and a weighted dictionary: each class has both a thesaurus weight (used for penalizing thesaurus substitutions) and a semantic term weight. With a classic thesaurus, there is a single penalizing thesaurus weight that is applied when equivalent but non-identical terms are matched between query and record. With a weighted dictionary, each equivalence class has a separate term weight that is applied to the terms whenever they occur in the query or a record. This increases or decreases the significance of matching or failing to match these terms.

To continue the Company Names example, in addition to designating terms like “Incorporated” as lightweight terms, you can add equivalences for common names and abbreviations such as “American Broadcasting Company” and “ABC”. You can enter these equivalences in the combined thesaurus table with a term weight of 1.0 (neither lightweight nor heavyweight), plus whatever thesaurus weight (substitution penalty) is required. You might require different substitution penalties for common company nicknames such as “IBM” and “Big Blue”. The combined thesaurus provides this flexibility in a single table.