Investigates document ranking methods in thesaurus-based Boolean information retrieval systems and proposes a new thesaurus-based ranking algorithm called the Extended Relevance algorithm. Performance comparisons are made between the Extended Relevance algorithm and previous thesaurus-based ranking algorithms. (Contains 20 references.) (LRW)

Reports research results into a methodology for determining similarity between queries characterized by Boolean search request formulations and discusses similarity measures for Boolean combinations of index terms. Rationale behind these measures is outlined, and conditions ensuring their equivalence are identified. Results of an experiment…

Presents new methods for compressing bit matrices in large information retrieval systems which exploit possible correlations between rows of words and columns of documents. Three encoding methods are tested and compared--Shannon-Fano, arithmetic, and Huffman--and an appendix discusses binomial coefficients. (20 references) (LRW)

Reports on a study of the size of text windows, defined as a group of words appearing in contiguous position in text, and the effects of varying the window size on information retrieval performance. The characteristics of windows that best match terms in queries are examined in detail. (Contains 10 references.) (KRN)

Discussion of information retrieval, knowledge representation, and computer-assisted learning focuses on a study that created a computer-based system designed to observe and record users' interactions with an ideal knowledge base consisting of unrevealed subject experts, appropriate documentation, and computer files. Information accessing…

Discussion of online bibliographic database searches focuses on a software system, SORT-AID/SABRE, that ranks retrieved citations in terms of relevance. Results of a comprehensive user evaluation of the relevance ranking procedure to determine its effectiveness are presented, and implications for future work are suggested. (10 references) (LRW)

Describes a study that identified both technical aptitudes and personality characteristics that are related to academic orientation variables previously found to predict information retrieval performance. It is argued that individual characteristics should be described so that they can be accommodated through design and training. (74 references)…

Describes method of automatic document classification in which documents classed as QA by Library of Congress classification system were clustered at six thresholds by keyword using single link technique. Automatically generated clusters were compared to Library of Congress subclasses, and partial classified hierarchy was formed. Twelve references…

Describes a study of medical students that was conducted to evaluate measures of performance on factual searches of INQUIRER, a full-text database in microbiology. Measures relating to recall, precision, search term overlap, and efficiency are discussed; reliability and construct validity are considered; and implications for future research are…