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Communications of the ACM

Table of Contents

A program to teach programming

The TEACH system was developed at MIT to ease the cost and improve the results of elementary instruction in programming. To the student, TEACH offers loosely guided experience with a conversational language which was designed …

Experiments with the M & N tree-searching program

The M & N procedure is an improvement to the mini-max backing-up procedure widely used in computer programs for game-playing and other purposes. It is based on the principle that it is desirable to have many options when making …

Measurements of segment size

Distributions of segment sizes measured under routine operating conditions on a computer system which utilizes variable sized segments (the Burroughs B5500) are discussed. The most striking feature of the measurements is the …

On an algorithm for nonlinear minimax approximation

Certain nonlinear minimax approximation problems are characterized by properties which permit the application of special algorithms, mainly based on the exchange algorithms of Remes (1934, 1935), for their solution. In this paper …

A comparison of error improvement estimates for adaptive trapezoid integration

Various simple choices of error improvement estimates for the trapezoid rule are studied to demonstrate a comparison procedure which is relatively independent of the profusion of adaptive search and stopping strategies. Comparisons …

A deductive question-answerer for natural language inference

The question-answering aspects of the Protosynthex III prototype language processing system are described and exemplified in detail. The system is written in LISP 1.5 and operates on the Q-32 time-sharing system. The system's …

PDEL—a language for partial differential equations

Conventional computer methods available to solve continuous system problems characterized by partial differential equations are very time-consuming and cumbersome. A convenient, easy to learn and to use, high level problem oriented …

Algorithms 377: Symbolic expansion of algebraic expressions [R2]

Certification of algorithm 310 [A1]: prime number generator

Remark on algorithm 336 [H]: Netflow

A number system for the permutations

A number system described here is particularly suitable for numbering the permutations. An algorithm is then presented by which the permutation associated with a number of this kind may be obtained. Since arithmetical operations …

Another method of converting from hexadecimal to decimal

There is a simple paper-and-pencil method of converting arithmetic a hexadecimal number N to decimal.

A note on the complement of inherently ambiguous context-free languages

Definitions and notation used in this note are as in [1]. In particaular, language means context-free language throughout.