Focuses on the user and human-computer interaction aspects of the research based on the Okapi text retrieval system. Three experiments implementing different approaches to query expansion are described, including the use of graphical user interfaces with different windowing techniques. (Author/LRW)

An online library catalog was used to evaluate an interactive query expansion facility based on relevance feedback for the Okapi, probabilistic, term weighting, retrieval system. A graphical user interface allowed searchers to select candidate terms extracted from relevant retrieved items to reformulate queries. Results suggested that the…