Efthimiadis, E.N. and Biron, P.V. "UCLA-Okapi at TREC-2: Query expansion experiments." In: The Second Text Retrieval Conference (TREC-2). Harman, D.K., ed. Proceedings of the Second Text Retrieval Conference, 31 August – 2 September, 1993, Gaithersburg, MD, USA. National Institute of Standards and Technology, Gaithersburg, MD. NIST-SP 500-215, March 1994, pp 279-290. [Conference paper]

This is the first participation of the Graduate School of Library and Information Science, University of California at Los Angeles in the TREC Conference. For TREC-2, Category B, UCLA used a version of the Okapi text retrieval system that was made available to UCLA by City University, London, UK. OKAPI has been described in TREC-1 (Robertson, Walker, Hancock-Beaulieu, Gull & Lau, 1993a) as well as in this conference (Robertson, Walker, Jones, Hancock-Beaulieu, & Gatford, 1994). Okapi is a simple set-oriented system based on a generalized probabilistic model with facilities for relevance feedback. In addition OKAPI supports a full range of deterministic Boolean and quasi-Boolean operations.