Supporting web query expansion efficiently using multi-granularity indexing and query processing

The problem of word mismatch in information retrieval (IR) occurs because u sers often use different words to describe concepts in their queries than a uthors use to describe the same concepts in their documents. Query expansio n is used to deal with the mismatch between author and user vocabularies. T o support query expansion, indices on words related by lexical semantics an d syntactical co-occurrence need to be maintained. Two issues become paramo unt in supporting query expansion: the size of index tables and the query p rocessing overhead. In this paper, we propose to use the notion of multi-gr anularity for more efficient indexing and query processing while the same d egrees of precision and recall are maintained. We also describes extensions of this technique to handle: (1) query relaxation to handle words with mul tiple senses and with other semantic relationships; (2) progressive process ing of queries with top N results and (3) progressive processing of queries with specification of the importance of each keyword. (C) 2000 Elsevier Sc ience B.V. All rights reserved.