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Communications of the ACM

Table of Contents


ACM president's letter: 100,000 in 1975!


An interactive command generating facility

A facility to permit conversationally controlled tasks to be executed in a noninteractive environment is proposed. A means by which programs can generate interactive time-sharing commands and receive the corresponding output  …

Conversational access to a 2048-word machine

LAP6 is an on-line system running on a 2048-word LINC which provides full facilities for text editing, automatic filing and file maintenance, and program preparation and assembly. It focuses on the preparation and editing of  …

The mobile programming system: STAGE2

STAGE2 is the second level of a bootstrap sequence which is easily implemented on any computer. It is a flexible, powerful macro processor designed specifically as a tool for constructing machine-independent software. In this …

Space/time trade-offs in hash coding with allowable errors

In this paper trade-offs among certain computational factors in hash coding are analyzed. The paradigm problem considered is that of testing a series of messages one-by-one for membership in a given set of messages. Two new hash …

File structures using hashing functions

A general method of file structuring is proposed which uses a hashing function to define tree structure. Two types of such trees are examined, and their relation to trees studied in the past is explained. Results for the probability …

Algorithm and bound for the greatest common divisor of n integers

A new version of the Euclidean algorithm for finding the greatest common divisor of n integers ai and multipliers xi such that gcd = x1 a1 + ··· + xn an is presented. The number of arithmetic operations and the number of storage …

Context-sensitive parsing

This paper presents a canonical form for context-sensitive derivations and a parsing algorithm which finds each context-sensitive analysis once and only once. The amount of memory required by the algorithm is essentially no more …

Algorithm 385: Exponential integral Ei(x)


Algorithm 386: Greatest common divisor of n integers and multipliers


Certification of algorithm 22: Ricatti-Bessel functions of first and second kind


Certification of algorithm 385: Exponential integral Ei (x)


Remarks on Algorithm 332: Jacobi polynomials: Algorithm 344: student's t-distribution: Algorithm 351: modified Romberg quadrature: Algorithm 359: factoral analysis of variance


Comments on a paper by Lowe

We have read with much interest the paper “Automatic Segmentation of Cyclic Program Structures Based on Connectivity and Processor Timing” by T. C. Lowe [Comm. ACM 13, 1 (Jan. 1970), 3-6, 9], and we congratulate the author on …

A note on data base deadlocks

In “Synchronization in a Parallel-Accessed Data Base” [Comm. ACM 12, 11 (Nov. 1969), 604-607] A. Shoshani and A. J. Bernstein have given a very lucid synthesis of diverse techniques to assure the integrity of a data base. But …

Note on an anomaly in paging

In [1] the authors use a lemma to prove their Theorem 1 (pp. 352-353). While the lemma is true, there is a defect in its proof, for one cannot assume that each of the symbols appearing as a type IV reference is in t(Ek , s).k …

A comment on axiomatic approaches to programming

Reference is made to the paper by C. A. R. Hoare [1] which discusses the fundamentals of an axiomatic approach to computer programming. One advantage for an axiomatic system proposed by Hoare is that an axiomatic description  …