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Communications of the ACM

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ACM President's Letter: October 14, 1980


Computer programs for detecting and correcting spelling errors

With the increase in word and text processing computer systems, programs which check and correct spelling will become more and more common. Peterson investigates the basic structure of several such existing programs and their …

Learning and reasoning by analogy

We use analogy when we say something is a Cinderella story and when we learn about resistors by thinking about water pipes. We also use analogy when we learn subjects like economics, medicine, and law. This paper presents a theory …

Deletion in two-dimensional quad trees

An algorithm for deletion in two-dimensional quad trees that handles the problem in a manner analogous to deletion in binary search trees is presented. The algorithm is compared with a proposed method for deletion which reinserts …

Measured performance of an Ethernet local network

The Ethernet communications network is a broadcast, multiaccess system for local computer networking, using the techniques of carrier sense and collision detection. Recently we have measured the actual performance and error characteristics …

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