Structuring and Expanding Queries in the Probabilistic Model.
Yasushi Ogawa, Hiroko Mano, Masumi Narita, Sakiko Honma · 1999
This is our first participation in TREC and five runs were submitted for the ad-hoc main task. Our system is based on our Japanese text retrieval system [4], to which English tokenizer /stemmer has been added to process English text. Our indexing system stores term positions, thus providing proximity-based search, in which the user can specify the distance between query terms. What our system does is outlined as follows: 1. Query construction The query constructor accepts each topic, extracts words in each of the appropriate fields and constructs a query to be supplied to the ranking system. 2. Initial retrieval The constucted query is fed into the ranking system, which then assigns term weights to query terms, scores each document and turns up a set of top-ranking documents assumed to be relevant to the topic (pseudo-relevant documents). 3. Query expansion Based on the feedback from the pseudo-relevant documents, the query expander collects and ranks the w