Discusses the adaptive compression of computer files of numerical data whose statistical properties are not given in advance. A new lossless coding method for this purpose, which utilizes Adelson-Velskii and Landis (AVL) trees, is proposed. The method is effective to any word length. Its application to the lossless compression of gray-scale images…

A review is given of doubly-chained trees for information retrieval. It is shown that the chaining steps may be of different cost depending upon whether the step is vertical or horizontal. The problem of constructing an optimal retrieval tree is formulated mathematically and a solution procedure given. (5 references) (Author/KE)

Proposes a cost/benefit model coupled with a decision tree for determining normal forms, which are used in information systems development processes to group data into well-refined structures. The three primary variables that impact the benefits and costs of normalization (reduced anomalies, storage requirements, and transaction response times)…

Examines two models to study the consequences for coding efficiency of sample fluctuations, a specific type of error in the statistics on which data compression codes are based. The possibility that random fluctuation can be exploited for data compression is discussed. (six references) (KRN)

False drops occur in a system of random superimposed coding for edge-notched, punched, and feature cards. Formulae for the false dropping fraction are derived, and figures and tables are given for the calculated values in the most popular scheme. (Author/LS)

Proposes a new conceptual basis for visualizing the organization of information, or knowledge, which differentiates between the concept "vectors" for a field of knowledge represented in a multidimensional space, and the state "vectors" for a person based on his understanding of these concepts, and the representational…

A new method for concentrating keywords of a thesaurus, based on a mathematical study of the distribution of characters in a defined natural language. (Author/KP)

A new technique, known as discrimination value analysis, ranks the text words in accordance with how well they are able to discriminate the documents of a collection from each other. (Author/PF)

Describes a method for compressing tomographic images obtained using Positron Emission Tomography (PET) and Magnetic Resonance (MR) by applying transform compression using all available dimensions. This takes maximum advantage of redundancy of the data, allowing significant increases in compression efficiency and performance. (13 references) (KRN)

Discusses a flexible, high performance subband coding system. Residual vector quantization is discussed as a basis for coding subbands, and subband decomposition and bit allocation issues are covered. Experimental results showing the quality achievable at low bit rates are presented. (13 references) (KRN)

A simulation of Cincinnati mass media system predicts frequency and reach of flow of messages from known facts taken from census statistics, newspaper and radio audience studies, and a content analysis of the press relevant to attitudes and opinions measured by NORC survey of the effects of a public information campaign on the United Nations made…

Least cost decision rules for transferring documents from primary to secondary storage are developed from a dynamic programing model of an information system. The program is constrained to provide for a minimum acceptable level of user benefits. Knowledge of the physical size of the primary storage area and the fraction of documents returned from…

Proposes a scheme of hierarchical piecewise linear approximation as an adaptive image pyramid. A progressive image coder comes naturally from the proposed image pyramid. The new pyramid is semantically more powerful than regular tessellation but syntactically simpler than free segmentation. This compromise between adaptability and complexity…

Describes a detailed algorithm for fast text compression. Related to the PPM (prediction by partial matching) method, it simplifies the modeling phase by eliminating the escape mechanism and speeds up coding by using a combination of quasi-arithmetic coding and Rice coding. Details of the use of quasi-arithmetic code tables are given, and their…

Describes the design of optimal tree-structured vector quantizers that minimize the expected distortion subject to cost functions related to storage cost, encoding rate, or quantization time. Since the optimal design problem is intractable in most cases, the performance of a general design heuristic based on successive partitioning is analyzed.…