In discussion about search keys, concern has been expressed as to how the number of items retrieved by a single value relates to collection size. This paper creates a statistical model that attempts to give some insight into this behavior. (6 references) (Author)

The direct-chaining technique of hash coding is generalized in a manner that is useful for storing records on the basis of non-unique search keys. Two hash functions are used, a process implying a tree structure. Two models, one involving unique and the other non-unique keys, are presented. (7 references) (Author/KE)

Recently considerable attention has been given in the online information retrieval literature to techniques for producing a weighted output of documents in response to a request. One approach tries to maintain the form of and relationships among requests as they appear in current Boolean logic-based systems, while extending it to permit a weighted…

Discusses the problem of how to permit a patron to represent the relative importance of various index terms in a Boolean request while retaining the desirable properties of a Boolean system. (FM)

Presents a model that places Boolean database queries into conjunctive normal form, thereby allowing probabilistic ranking of documents and the incorporation of relevance feedback. Experimental results compare the performance of a sequential learning probabilistic retrieval model with the proposed integrated Boolean probabilistic model and a fuzzy…

Presents decision-theoretic models which intrinsically include retrieval of multiple documents whereby system responds to request by presenting documents to patron in sequence, gathering feedback, and using information to modify future retrievals. Document independence model, set retrieval model, sequential retrieval model, learning model,…

Examines consequences for information control of the tendency of occurrences of content-bearing terms to appear together, or clump. Properties of previously defined clumping measures are reviewed and extended, and significance of these measures for devising retrieval strategies discussed. A new type of clumping measure, which extends the earlier…