Proposes split model for index term distribution in document set that uses rank function for high frequency terms and size function for low frequency terms; the point of transition is determined either empirically or by rule. Distributions to describe index term exhaustivity and term co-occurrence are considered briefly. (36 references) (EJS)

Discussion of a new method of index term dictionary compression in an inverted-file-oriented database highlights a technique of word coding, which generates short fixed-length codes obtained from the index terms themselves by analysis of monogram and bigram statistical distributions. Substantial savings in communication channel utilization are…

Describes research which measured the efficiency of role operators through frequency of appearances in PRECIS input strings for 200 abstracts related to taxation, genetic psychology, and Shakespearian drama. Frequencies of appearance of major categories of role operators, role operators in different subjects, individual main line operators, and…

This update of 1978 bibliometric study of online retrieval literature reveals that: literature has continued to grow, reaching peak annual output (504 papers) in 1981; conference literature has become centralized in four major proceedings; online retrieval papers have appeared in 479 journals; and 31 authors have contributed 10 or more papers.…

Presents a coordination level matching algorithm to be used in document retrieval systems that incorporate relevance feedback strategies. It is argued that this algorithm may eliminate the need for the frequent reevaluation of documents that is currently found in such systems, and conditions under which reranking is unnecessary are given.…

Describes probabilistic document retrieval systems as a sequential learning process, in which the system learns the parameters of probability distributions describing the frequencies of feature occurrences in relevant and nonrelevant documents. Several techniques for estimating the parameters of distributions are described and the results of tests…

Describes a document retrieval system that provides for user interaction at several search stages to acquire a detailed specification of the user's information need. The use of domain knowledge to refine the query and a browsing mechanism are described in detail, and further research questions are identified. (CLB)

Reports algorithm for calculation of term discrimination values that is sufficiently fast in operation to permit use of exact values. Evidence is presented to show that relationship between term discrimination and term frequency is crucially dependent upon type of inter-document similarity measure used for calculation of discrimination values. (13…

Describes study that compared terminology indexing and citation indexing to determine the similarity of documents retrieved. Information science articles from 1971 to 1983 in three journals were studied for term co-occurrences. The distinction between relevant and pertinent documents is discussed, and further research topics are suggested. (LRW)

Zipfian laws for frequency distributions of word pairs and longer phrases are derived from text sample analysis. From crossing of Zipfian curves, it is deduced that number of multi-word phrases that occur frequently in text is surprisingly small, of same order of magnitude as number of individual word-types. (8 references) (EJS)