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Communications of the ACM

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ACM President's Letter: Sakharov


Attribute based file organization in a paged memory environment

The high cost of page accessing implies a need for for more careful data organization in a paged memory than is typical of most inverted file and similar approaches to multi-key retrieval. This article analyses that cost and  …

A cell organized raster display for line drawings

Raster scan computer graphics displays with “real time” character generators have previously been limited to alphanumeric characters. A display is described which extends the capabilities of this organization to include general …

An approximate method for generating asymmetric random variables

Tukey's lambda distribution is generalized to provide an algorithm for generating values of unimodal asymmetric random variables. This algorithm has the same advantages as the symmetric random variable generator previously given …

The parallel execution of DO loops

Methods are developed for the parallel execution of different iterations of a DO loop. Both asynchronous multiprocessor computers and array computers are considered. Practical application to the design of compilers for such computers …

Production systems: or can we do better than BNF

Since the development of BNF, the definition of the syntax of programming languages has been almost universally associated with context-free requirements. Yet numerous interesting and difficult issues in syntax stem from the  …

The synthesis of loop predicates

Current methods for mechanical program verification require a complete predicate specification on each loop. Because this is tedious and error prone, producing a program with complete, correct predicates is reasonably difficult …

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