1-1


                                 CHAP~ER 1


                                I~TRODUCTION


1.  The ~ocument Retrieval Problem


         The attention devoted to document retrieval systems in recent

years is based in some form or other on the assumption that such systems

can satisfy needs exhibited by a class 0£ users or can satisfy needs

likely to be exhibited in the near future.   Although there is general

agreement that situations re~uiring reference to some body of accumulated

knowledge do exist in~modern society, there is no such consensus as to

the most effective means 0£ satisfying such needs underthe varying sets

of circumstances' in which'they      2,3,4,5,6. One 0£ the alternatives
                                arisee

und'er consideration~is the' application of automatic information

processing equipment~, to the mechanization of reference providing

systems.7  This report' characterizes the basic functions required in such

systems, and develops' optimization techniques. app' licable tq a certain

class:o£ implementations of `these functionse  In addition,the basis for

the evaluation of retrieval system performance is examined and some novel

evaluation criteria are introduced.

         In general terms the document retrieval,problem can be

introduced with the following assumptions:   a body of recorded knowledge


    The reference's cited in the introduction are only illustrative and
    are by~no~ means exhaustivee  The Proceedings of t~ 1958
    International Conference on `Scientific Information Qontains a
    number of papers dealing with doc~ent retrieval and ~l: ie'd problems.