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Ordered sets (OS) of documents are encountered more and more in information distribution systems, such as information retrieval systems. Classical similarity measures for ordinary sets of documents need to be extended to these ordered sets. This is done in this article using fuzzy set techniques. The practical usability of the OS-measures is discussed based on the experiments described. (Author/AEF)

Studies concentration aspects of bibliographies, particularly the impact of incompleteness on its concentration values (i.e. its degree of inequality of production of its sources). Models incompleteness by different sampling techniques and discusses implications for the measurement of production inequality in incomplete bibliographies. (Author/LRW)

Discussion of fractional frequency distributions of authors with a certain (fractional) number of papers focuses on the use of Lotka laws to model theoretical fractional frequency distributions with one parameter. Shows that irregular fractional frequency distributions are a consequence of Lotka's law, not breakdowns of the law. (Author/LRW)

Presents a general method to construct ordered similarity measures in information retrieval based on classical similarity measures for ordinary sets. Describes a test of some of these measures in an information retrieval system that extracted ranked document sets and discuses the practical usability of the ordered similarity measures. (Author/LRW)

Studies the relation between journal median citation age and the number of articles in the journal. Discusses statistical explanations, including graphs of clouds of points and the Central Limit Theorem; and considers explanations of regularities in informetrics, based on statistical, probabilistic, or informetric results. (Author/LRW)

Zipf's law states that if words in a text are arranged in decreasing order of occurrence, then the product of the rank of a word and the number of times it occurs is a constant of that text. Examination of the probabilities of occurrence of multi-word phrases in information retrieval in relation to the probabilities of occurrence of single words proves that for multi-word phrases Zipf's law is not valid. (AEF)

Describes RECOSCIX-WIO (Regional Cooperation in Scientific Information Exchange in the Western Indian Ocean Region). Details are given on the project's history, operational structure, and communication facilities, as well as services and products including query handling and document delivery. Future plans are also discussed, including CD-ROMs and a World Wide Web server. (Author/LRW)

Proves price index (proportion of references within the last five years of literature) is not a pure function of the mean or median reference age, but a well-defined relation in the form of a typical cloud of points. Compares models for analyzing price index (decreasing exponential and lognormal aging) and explains cloud using results from probability theory and statistics. (PEN)

Discusses information production processes (IPP)--i.e., continuous mathematical models of production processes such as bibliographies, economic production processes, and social usages of words in a text--from the point of view of concentration theory. Gini's index is studied in the dual framework of IPPs. (27 references) (LRW)

Discusses the shape of the obsolescence function based on the age data for cited journals. An analysis of the aging function is discussed; and statistical fits and mathematical explanations are illustrated, including the model of Avramescu, the Negative Binomial Distribution, the Weibull distribution, the lognormal distribution, and the utility functions. (20 references) (LRW)

Discusses the theory of collaboration and measures of collaboration. Variables for collaborative measures are considered, principles are formulated that good collaborative measures should satisfy, examples and practical calculations are presented, and further problems for research are suggested. (nine references) (LRW)

Discusses normalization features of good concentration measures and extends the range of values of concentration measures that are population-size-independent. Rational normalization is described, and mathematical formulas for the coefficient of variation, Pratt's measure, the Gini index, Theil's measure, and Atkinson's indices are explained. (14 references) (LRW)

Demonstrates that the multiplier that appears in the law of Bradford is not the average production of articles per author nor the average number of articles per journal, contradicting some earlier statements by Goffman and Warren and of Yablonsky. Other mathematical properties of Bradford's law are explored. (15 references) (Author/CLB)

Reports data on the application of Bradford's law to several classical bibliographies, for which the underlying law of Leimkuhler and various Bradford groupings are determined. The Leimkuhler law is extended to be applicable to incomplete bibliographies and to the estimation of complete bibliographies from incomplete bibliographies. Formulas and data tables are included. (17 references) (MES)