ISR10 Evaluation of Document Retrieval Systems chapter Joseph John Rocchio Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. 5-22 define a function r*(x) equal to r*(i) for x =.i, a possible anomaly is noted. This arises from the fact that it is possible, within the framework of the system, for N to produce a mapping from elements of q x to the real line. This, in fact, occurs when N is a correla- tion process which correlates a query image with the set of document images viewed as vectors in some abstract space. The process of inducing an ordering from this mapping and then treating this ordering as a function of a continuous real variable gives the impression of coming full circle. In fact, there is clearly a loss of information involved since relative distance between the images of d. and d. is not 1 preserved by this process. The justification for msking this transforma- tion from the domain of N to an ordering index lies in the assumption that the order so derived has significance of and by itself. The extension then to functions of a real variable is accomplished by defining two functions r*(x) and p*(x) such that: r*(x) = r*(i) > for x = i, i = p*(x) = p*(i)) and further that: ( -[OCRerr] for j[OCRerr] x< j + 1 , and j integral and less than n0 r*(x) = 1 for x >n 0 and I - for j< x< j + 1., and j integral and p*(x) =I[OCRerr]xn less than n0 0 -forx>n 0