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Communications of the ACM

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Program verification: the very idea

The notion of program verification appears to trade upon an equivocation. Algorithms, as logical structures, are appropriate subjects for deductive verification. Programs, as causal models of those structures, are not. The success …

Learning by doing with simulated intelligent help

Intelligent advisory interfaces will afford new approaches to help and training problems, however little is known about the usability of such facilities. This recent study indicates that although intelligent help can support  …

Reading and writing with computers: a framework for explaining differences in performance

Several factors can influence the behavior of users as they read and write with computers. Recent research indicates that both quality and quantity depend upon page size, legibility, responsiveness and tangibility.

Comparison of analysis techniques for information requirement determination

A comparison of systems analysis techniques, the Data Flow Diagram (DFD) and part of the Integrated Definition Method (IDEFo), is done using a new developmental framework.

A comparison of techniques for the specification of external system behavior

The elimination of ambiguity, inconsistency, and incompleteness in a Software Requirements Specification (SRS) document is inherently difficult, due to the use of natural language. The focus here is a survey of available techniques …

The input/output complexity of sorting and related problems

We provide tight upper and lower bounds, up to a constant factor, for the number of inputs and outputs (I/OS) between internal memory and secondary storage required for five sorting-related problems: sorting, the fast Fourier …

Improving locality of reference in a garbage-collecting memory management system

Modern Lisp systems make heavy use of a garbage-collecting style of memory management. Generally, the locality of reference in garbage-collected systems has been very poor. In virtual memory systems, this poor locality of reference …

Technical correspondence