ISR11 The SMART System -- Retrieval Results and Future Plans chapter G. Salton Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. 1-2 manual ke[OCRerr][OCRerr]rd search process shows that many automatic prdcedures are fully as effective in retrieving useful materials and in rejecting useless ones as are the better known manual procedures. [i] Since an information system, whether manual or automatic, may be expected to service a large variety of customers, each of whom may have different needs and different background, it is unreasonable to suggest that a single search of some part of the collection would prove equally useful for all customers at all times. Accordingly, more emphasis has been placed in the recent past on search experiments using storage organi- zations and search strategies which make it possible for the user to influence the search results by submitting to the system appropriate feedback information. A given search is then undertaken iteratively by processing the same search request several times, while altering the search conditions for each iteration. Such iterative retrieval techniques are particularly well adapted to automatic time-sharing equipment [OCRerr][OCRerr]here customers can conmumicate directly [OCRerr]71th the system by means of suitable input-output equipment. [2,3] Many different user feedback strategies have been considered experi- mentally [[OCRerr]], as well as a variety of search strategies. Some search strategies, based on' the construction of groups of related documents, and groups of related search requests seem particularly promising, since they make it possible to obtain effective retrieval performance by co[OCRerr]aring a given search request against only a small number of selected documents, instead of performing a full search of the collection. [5,6] The procedure making use of document groups, or clusters, is'based on the identification of certain document subsets similar in some sense to