N-version programming has been proposed as a method of incorporating fault tolerance into software. Multiple versions of a program (i.e. "N") are prepared and executed in parallel. Their outputs are collected and examined by a voter,and, if theyare not identical, it is assumed that the majority is correct. This method depends for its reliability improvement on the assumption that programs that have been developed independently will fail independently.Inthis paper an experiment is described in which the fundamental axiom is tested. Atotal of twenty sevenversions of a program were prepared independently from the same specification at twouniversities and then subjected to one million tests. The results of the tests revealed that the programs were individually extremely reliable but that the number of tests in which more than one program failed was substantially more than expected. The results of these tests are presented along with an analysis of some of the faults that were found in the programs. Background information on the programmers used is also summarized. The conclusion from this experiment is that N-version programming must be used with care and that analysis of its reliability must include the effect of dependent errors. Keywords and Phrases: Multi-version programming, N-version programming, software reliability,fault-tolerant software, design diversity. * This work was sponsored in part by NASA grant number NAG1-242 and in part by a MICROgrant cofunded by the state of California and Hughes Aircraft Company. 1.

set of measurements from a large outdoor routing experiment, we start by evaluating the relative realism of common assumptions made in radio model design, identifying those which provide a reasonable approximation of reality. Although several such investigations have been made for static sensor

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philip.resnikfleast.sun.com This paper presents a new measure of semantic similarity in an IS-A taxonomy, based on the notion of information content. Experimental evaluation suggests that the measure performs encouragingly well (a correlation of r = 0.79 with a benchmark set of human similarity

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This paper describes a database designed to evaluate the performance of speech recognition algorithms in noisy conditions. The database may either be used to measure frontend feature extraction algorithms, using a defined HMM recognition back-end, or complete recognition systems. The source speech

This paper presents studies of the coordination of volun-tary human arm movements. A mathematical model is for-mulated which is shown to predict both the qualitative fea-tures and the quantitative details observed experimentally in planar, multijoint arm movements. Coordination is modeled

their performance depends on the interest region detector. The descriptors should be distinctive and at the same time robust to changes in viewing conditions as well as to errors of the detector. Our evaluation uses as criterion recall with respect to precision and is carried out for different image transformations

Abstract. This paper focuses on a comparative evaluation of a wide-range of text categorization methods, including previously published results on the Reuters corpus and new results of additional experiments. A controlled study using three classifiers, kNN, LLSF and WORD, was conducted to examine

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