IRS13 Thesaurus, Phrase and Hierarchy Dictionaries 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. VII-57 7. Any further testing of phrases of the type presently used, requires more exhaustive phrase lists. Tests could also be made in which phrases are given quite high weights; a strategy in which phrase identifiers would replace com- ponent concept identifiers would be of interest in this connection. 8. New types of phrase recognition procedures would be a better test of phrases than present methods. 9. New hierarchies based on stems or on some improved type of phrase procedures would require a large amount of con- struction effort; this possibility should not, however, be abandoned. 10. In thinking of the operational use of dictionaries, the design of methods for manually (or, automatically) gener- ating an accurate pre-search choice from a selection of dictionaries should be undertaken. Also, the present practice of looking up both requests and documents in a given dictionary seems to be unnecessary, since no additional matches between requests and documents are established if only the requests are processed. Expanding requests only might produce some advantage in an opera- tional user-interactive system, since some users would want to select and reject certain synonyms personally, and would not want to use rigid thesaurus groups at each stage. Evaluation of this suggestion is needed to determine the effect of expanding requests using only the weighting scheme and correlation functions in use. 11. The need to process foreign language documents has pre- viously been pointed out; a German translation of the ADI "ISPRA" Thesaurus is currently tested in this connection.