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Communications of the ACM

Table of Contents


ACM president's letter:Pixel Art


Software engineering for the Cobol environment

In a attempt to improve the productivity of their 70 development staff, Skandinaviska Enskilda Banken has built an integrated set of manual and automatic tools for the implementation of Cobol programs. It was possible to use  …

Self-assessment procedure X: a self-assessment procedure dealing with software project management


Computer professionals whose scientific freedom and human rights have been violated–1982: a report of the ACM committee on scientific freedom and human rights


On the emulation of flowcharts by decision tables

Any flowchart can be emulated by a decision table, whose complexity depends on that of the flowchart. It may be necessary, however, to introduce a new control variable with associated tests and sets or to permit changes in execution …

An effective way to represent quadtrees

A quadtree may be represented without pointers by encoding each black node with a quaternary integer whose digits reflect successive quadrant subdivisions. We refer to the sorted array of black nodes as the “linear quadtree”i …

Implementations for coalesced hashing

The coalesced hashing method is one of the faster searching methods known today. This paper is a practical study of coalesced hashing for use by those who intend to implement or further study the algorithm. Techniques are developed …

A critique of the foundations of Hoare style programming logics

Much recent discussion in computing journals has been devoted to arguments about the feasibility and usefulness of formal verification methods. Too little attention has been given to precise criticism of specific proposed systems …

A hash code method for detecting and correcting spelling errors

The most common spelling errors are one extra letter, one missing letter, one wrong letter, or the transposition of two letters. Deletion, exchange, and rotation operators are defined which detect and “mend” such spelling errors …

A comment on English neologisms and programming language keywords

The choice of keywords in the design of programming languages is compared to the formation of neologisms, or new words, in natural languages. Examination of keywords in high-level programming languages shows that they are formed …

Technical correspondence: on computer system messages. author's response


Technical correspondence: another approach to data compression


Technical correspondence: Another approach to data compression


ACM forum

This is a comment on “File Archival Techniques Using Data Compression” by Michael Pechura [Communications, Sept. 1982, p. 605]. We approached the data compression problem with the aim of maximizing the saving in archival storage …