This paper serves as an introduction to the research described in detail in the remainder of the volume. The next section defines the common retrieval tasks performed in TREC-6. Sections 3 and 4 provide details regarding the test collections and the evaluation methodology used in TREC. Section 5 provides an overview of the retrieval results. The final section summarizes the main themes learned from the experiments.

The object of Information Retrieval is to retrieve all relevant documents for a user query and only those relevant documents. Much research has focused on achieving this objective with little regard for storage overhead or performance. In the paper we evaluate the use of Part of Speech Tagging to improve, the index storage overhead and general speed of the system with only a minimal reduction to precision recall measurements. We tagged 500Mbs of the Los Angeles Times 1990 and 1989 document collection provided by TREC for parts of speech. We then experimented to find the most relevant part of speech to index. We show that 90% of precision recall is achieved with 40% of the document collections terms. We also show that this is a improvement in overhead with only a 1% reduction in precision recall.

The Text REtrieval Conference is a workshop series designed to encourage research on text retrieval for realistic applications by providing large test collections, uniform scoring procedures and a forum for organizations interested in comparing results. TREC contains two main retrieval tasks plus optional subtasks that allow participants to focus on particular common subproblems in retrieval. The emphasis on individual experiments evaluated in a common setting has proven to be very successful. In the six years since the beginning of TREC, the state of the art in retrieval e€ectiveness has approximately doubled, and technology transfer among research labs and between research systems and commercial products has accelerated. In addition, TREC has sponsored the ®rst large-scale evaluations of Chinese language retrieval, retrieval of speech and retrieval across di€erent languages. Published by Elsevier Science Ltd.