Communications of the ACM

Comments on program specification and testing

The data processing discipline is in a deplorable state, says Roger House. The author reviews an earlier study, in which programmers were largely unsuccessful in finding known errors in a test program. House shows that the fault … Roger House
Pages 324-331

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Computer assisted instruction: current trends and critical issues

The use of computers to assist in the learning situation in a simulation, game, tutorial, or drill and practice mode is reviewed on an international basis with centers of activity identified in the United States, Canada, the  … Jack A. Chambers, Jerry W. Sprecher
Pages 332-342

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An improved illumination model for shaded display

To accurately render a two-dimensional image of a three-dimensional scene, global illumination information that affects the intensity of each pixel of the image must be known at the time the intensity is calculated. In a simplified … Turner Whitted
Pages 343-349

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A more general algorithm for computing closed semiring costs between vertices of a directed graph

This note describes a generalization of an algorithm given by Aho, Hopcroft, and Ullman [1], originally derived from the work of Kleene [2] and McNaughton and Yamada [3]. The algorithm is used to compute the total cost of all … John G. Fletcher
Pages 350-351

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ACM forum

Robert L. Ashenhurst
Pages 355-359

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ACM President's Letter: “You have a call from Moscow”

Pages 322-323

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