IRS13 An Analysis of the Documentation Requests chapter E. M. Keen Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. X-37 synonyms made on an individual request basis should work better than the obligating use of the pre-constructed set of synonyms contained in the the- saurus. The hand searches do not use any feedback to obtain a fair comparison, since the search keywords were chosen before any reference was made to the KWIC concordance. The result of SMART using the hand modified "important11 concept with increased weights is included in Figure 21 b); the curve now lies much closer to the hand result. Naturally a hand system permitting coordinate keyword searches would extend the hand curve to higher precision values, and choices of more than five keywords per request would enable higher recall ratios to be reached. This result does not condemn the automatic indexing procedures, because hand searches are less easy to conduct in the sort of situation in which SMART would operate, such as a large file of individually long docu- ment surrogates. It is clear also that in an operational use of SMART; search strategies employing several dictionaries in a variety of possible ways could be used, and for users willing to employ some intellect to strongly interact with the system, quite large performance gains may be ex- pected. Ways in which a system might operate are: the use of several dic- tionaries successively, until the required performance is reached; the use of several dictionaries with 11merged11 output results [6]; use of a manual [OCRerr] or automatic method of making an accurate pre-search best dictionary choice, yet to be developed; use of dictionary display methods to allow users willing to strongly interact to delete or add synonyms; and the use of relevance feedback methods to iterate searches and improve performance. Of these suggestions the idea of making a pre-search dictionary choice has been explored but with no success so far. If, for example, long requests work better with the stem dictionary, and short requests need the