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Communications of the ACM

Table of Contents


Letters to the editor: on Bellman's method for unstable linear systems


Letter to the editor: on format effectors


Letter to the editor: a “subprofessional” comments


The simulation of time sharing systems

The development of new large scale time-sharing systems has raised a number of problems for computation center management. Not only is it necessary to develop an appropriate hardware configuration for these systems, but appropriate …

A user-oriented time-shared online system

An existing system and planned additions within the Data Processing Laboratory of the Brain Research Institute at UCLA is described. The system represents an attempt to provide research workers of the Institute with the ability …

String processing techniques

The internal organization of string processing systems is discussed. Six techniques for data structures are presented and evaluated on the basis of: (1) creation of strings; (2) examination of strings; and (3) alteration of strings …

Implementing phrase-structure productions in PL/I

A method is described for implementing the productions of a context-free phrase structure grammar in a PL/I procedure whose structure and statements parallel the structure and notation of the grammar.

Plotting a function of three independent variables

A method is developed for constructing an approximate plot of a function of three independent variables. The plot is similar to a conventional contour map except that there are three scales to represent the independent variables …

On the representation of symmetric polynomials

Relations are given between certain symmetric polynomials in the light of the theory of the symmetric group. Such an approach unifies earlier work and lends insight to previously published work by Aaron Booker. A generalization …

Optimal starting values for Newton-Raphson calculation of x1 2

The problem of obtaining starting values for the Newton-Raphson calculation of √x on a digital computer is considered. It is shown that the conventionally used best uniform approximations to √x do not provide optimal starting …

A language independent macro processor

The problem of obtaining starting values for the Newton-Raphson calculation of √x on a digital computer is considered. It is shown that the conventionally used best uniform approximations to √x do not provide optimal starting …

Description of basic algorithm DETAB/65 preprocessor

The basic algorithm for the conversion of decision tables into COBOL code is contained in the generator portion of the DETAB/65 preprocessor. The generator analyzes a decision table and produces simple COBOL conditional statements …

A method for finding Hamilton paths and Knight's tours

The use of Warnsdorff's rule for finding a knight's tour is generalized and applied to the problem of finding a Hamilton path in a graph. A graph-theoretic justification for the method is given.

Algorithm 305: symmetric polynomial


Algorithm 306: permutations with repetitions


Algorithms 307: Symmetric group characters


Remarks on algorithm 87, 102, 130, 202: generation of permutations in lexicographical order


Algorithm 308: Generation of the permutations in psedo-lexicographic order


Certification of algorithm 285: the mutual primal-dual method


Certification of algorithm 258: transport and algorithm 293: transportation problem


Remark on algorithm 301: Airy function


Changes in government procurement policies

Several years ago there was an attempt in Washington to place the selection of government computers in a central, highly placed office. Individual government agencies, led by the Department of Defense, successfully beat back  …