The user's query must be seen as a dynamic set of words and phrases which may be altered both by the system and by the user during a search session. Most initial queries contain too little information to retrieve all the items in a database about a particular topic, so the system should act intelligently to help formulate and re-formulate, in order to obtain better results.
In principle, an interactive retrieval system can assist with initial query formulation before the first search is undertaken. In particular, preliminary use of the thesaurus may allow the system to identify:
These approaches were explored in the earlier CILKS project, where users entering a query were presented with a set of partial matches from the thesaurus, and encouraged to undertake further navigation to identify other possibly relevant terms. In practice, however, users found it difficult to judge the potential value of new terms without seeing real documents --- hence the emphasis in the current project on combining thesaurus consultation with other forms of query expansion.
The ENQUIRE system implements only the first of the preliminary processes listed above. Phrases which are exact matches of thesaurus terms are identified and used immediately --- synonym identification and general thesaurus navigation based on partial matching become operative only after the first search, to support the process of query re-formulation. The designers identified three main types of query reformulation which the interface should support:
Section 2.3 in the previous chapter describes how the system identifies suggested thesaurus terms, and performs incremental query expansion. Sections 3.6.2 and 3.6.3 below describe how these activities are presented to users.