Back to ComputerTerms, InformationRetrieval '''Key: * Increases ["Recall"]''' * Not necessary for many queries and are generally of marginal use. Using information about the relevance of results from previous searches to modify current queries is a form of RelevanceFeedback. Types? * Reweighting without Query expansion - This is where we reweight the terms * Query expansion without reweightng - Ideally, query expansion should be done using a thesaurus that adds sysnonyms. * Query expansion with reweighting Back to ComputerTerms, InformationRetrieval