Query Expansion and Relevance Feedback

Query Expansion describes the set of techniques for modifying a query in order to satisfy an Information Need. In most cases, terms are added to an existing query, although Query Expansion also encompasses techniques for the reweighting of terms as well as the deletion of terms. Query Expansion techniques can be partitioned into three sets:

Manual

Manual Query Expansion (MQE) refers to techniques that a user may employ to modify the query. The system does not aid the user at all.

Automatic

Automatic Query Expansion (AQE) refers to techniques that modify a query without user control. For example, a system that always adds thesaurus terms to a query would be considered an AQE system.

Interactive

Interactive Query Expansion (IQE) refers to techniques where the user has some interaction with the system in the query expansion process. This set of techniques encompasses Relevance Feedback and is the focus of this paper.

Manual and Automatic Query Expansion techniques are beyond the scope of this paper, and since the literature concerning those topics is quite large and diverse, interested readers are referred to a 1996 survey paper by Efthimiadis [13].