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Communications of the ACM

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ACM president's letter: the roles of ACM: III. ACM and other societies


A computer science course program for small colleges

The ACM Subcommittee on Small College Programs of the Committee on Curriculum in Computer Science (C3S) was appointed in 1969 to consider the unique problems of small colleges and universities, and to make recommendations regarding …

Common phrases and minimum-space text storage

A method for saving storage space for text strings, such as compiler diagnostic messages, is described. The method relies on hand selection of a set of text strings which are common to one or more messages. These phrases are  …

Telecommunications using a front-end minicomputer

The use of a front-end minicomputer to provide varied remote terminal access to a large scale computer is considered. The problems of embedding telecommunications I/O within an operating system are discussed, and it is shown  …

The effects of multiplexing on a computer-communications system

A study is made of the way in which asynchronous time division multiplexing changes the stochastic nature of the arrival process from a user to the computer and, consequently, affects the performance of a time-shared computer …

Design and implementation of a diagnostic compiler for PL/I

PL/C is a compiler for a dialect for PL/I. The design objective was to provide a maximum degree of diagnostic assistance in a batch processing environment. For the most part this assistance is implicit and is provided automatically …

On Harrison's substring testing technique

This note comments on a technique by Malcolm Harrison [1] that tests whether a given string of characters, S1, is a substring of another string of characters, S2. This technique first transforms S2 into the set consisting ofk …

Graduate education: the Ph.D. glut

[Two years ago the author was elected by the Washington State University faculty to a three-year term as a faculty representative to a Graduate Studies Committee charged “to examine and evaluate proposed changes in the policy …

Algorithm 444: an algorithm for extracting phrases in a space-optimal fashion


Algorithm 445: Binary pattern reconstruction from projections


Forum


Gray code and the ± sign sequence when ±f(±f(±f(•••±f(x)•••))) is ordered

A previous note gives a rule for determining the sequence of + and - signs to obtain the ith largest value of +ƒ(±ƒ(±ƒ(··· ±ƒ(x)···))) when ƒ(x) is positive and monotonic [1, p. 46, §2]. Shortly after publication the writer received …