Allowing users to weight search

Information retrieval systems typically weight the importance of search terms according to document and collection statistics (such as by using tf idf scores, where less common terms are given higher weight). We consider here the scenario where a user can express her own subjective weighting of the importance of the terms that form the query on top of the system-generated weighting, and show how this should modify the relevance scores of documents. This has been allowed before, but only by ad hoc heuristics. We give the rst principled method for taking into account the user's subjective weighting of the importance of query terms. Our method is based on an approach by Fagin and Wimmers, that gives a simple formula derived from any existing \unweighted" ranking function. A naive application of the formula would require issuing as many distinct queries as there are terms in the query (search terms), thus damaging the response time of the retrieval. We explain here how to \smoothly" integrate the formula in most information retrieval systems so as not to aaect the retrieval performance in terms of response time.