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Communications of the ACM

Table of Contents


President's Letter


ACM forum


DoD procurement in transition


Is Ada too big? A designer answers the critics

Many have criticized the Department of Defense's new computer language, Ada, saying it is too large, too complicated, or too difficult to use. Are they right? And are there some simplifications that could be made to Ada without …

The operational versus the conventional approach to software development

The conventional approach to software development is being challenged by new ideas, many of which can be organized into an alternative decision structure called the “operational” approach. The operational approach is explained …

The coordinated use of five performance evaluation methodologies

Information system design can be influenced and ultimate performance parameters accurately forecast through the coordinated use of five performance analysis tools. The complementary methodology is used to first predict and then …

Online help systems: a conspectus

Users of computer systems are now accustomed to the convenience of online help systems and generally demand these amenities in the computers they buy. However, recent studies as to the efficacy of certain types of assistance  …

Predicative programming Part I

Programs are given a new semantics with the merit that a specification written as a first-order predicate can be refined, step by step, to a program via the rules of Predicate Calculus. The semantics allows a free mixture of  …

Predicative programming Part II

Part I of this two-part paper presented a new semantics of programs. Each program is considered to be a predicate, in a restricted notation, that specifies the observable behavior of a computer executing the program. We considered …

Corrigendum 1: A quadtree medial axis transform by Hanan Samet. Commun. ACM 26, 9 (Sept. 1983), 680-692


Corrigendum 2: An analysis and algorithm for polygon clipping by You-Dong Liang and Brian A. Barsky. Commun. ACM 26, 11 (Nov. 1983), 868-877


Chain mulitplication of matrices of approximately or exactly the same size

We present a different approach to finding an optimal computation order; it exploits both the difference between the size of the matrices and the difference between the number of nonzero elements in the matrices. Therefore, this …