On Expanding Query Vectors with Lexically Related Words

Experiments performed on small collections suggest that expanding query vectors with words that are lexically related to the original query words can improve retrieval eeectiveness. Prior experiments using WordNet to automatically expand vectors in the large TREC-1 collection were inconclusive regarding eeec-tiveness gains from lexically related words since any such eeects were dominated by the choice of words to expand. This paper speciically investigates the eeect of expansion by selecting query concepts to be expanded by hand. Concepts are represented by WordNet synonym sets and are expanded by following the typed links included in WordNet. Experimental results suggest that this query expansion technique makes little diierence in retrieval eeectiveness within the TREC environment , presumably because the TREC topic statements provide such a rich description of the information being sought.