ISR10 Search Request Formulation 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. feedback modified Queries. Figures [OCRerr].8 and [OCRerr] compare the retrieval results of two additional original and relevance feedback queries. [OCRerr]ote that for the query "Analog-Digital1 shown in Figure 3.[OCRerr], one of the relevant documents namely document 46, experiences a decrease in its retrieved rank from 21st to 46th while the ranks of the other relevant documents are substantially improved. This may be interpreted as implying that the index image of document 46 is less associated (in terms of angular distance in the index space) with the other relevant documents than it is with the original query. In general, this effect occurs, whenever the index images of the documents relevant to a search request form distinct clusters in the index space, and when the set of relevant documents identified by the relevance feedback consists substantially of members from only one of these clusters. In some cases it will be possible to identify such situations, and autqmatically to generate multiple queries for such search requests. For the case in point, however, the single document (no. 46) is assumed not to be identified by the original query. In this instance, then, there is no effective way to increase the probability of retrieving it. Such situations must then be interpreted (assuming that there are no grounds on which to question a user1s relevance judgments), aQ arising from deficiencies in the indexing[OCRerr] process or from the inherent information loss which necessarily accompanies it. B. Average Results and Successive Iterations The query modification procedure as illustrated in the