The consistent comparison problem in N-version software

Author

Brilliant, Susan S. ; Knight, John C. ; Leveson, Nancy G.

Author_Institution

Dept. of Math. Sci., Virginia Commonwealth Univ., Richmond, VA, USA

Volume

15

Issue

11

fYear

1989

fDate

11/1/1989 12:00:00 AM

Firstpage

1481

Lastpage

1485

Abstract

The authors have identified a difficulty in the implementation of N-version programming. The problem, called the consistent comparison problem, arises for applications in which decisions are based on the results of comparing finite-precision numbers. It is shown that when versions make comparisons involving the results of finite-precision calculations, it is impossible to guarantee the consistency of their results. It is therefore possible that correct versions may arrive at completely different outputs for an application that does not apparently have multiple correct solutions. If this problem is not dealt with explicitly, an N-version system may be unable to reach consensus even when none of its component versions falls

Keywords

fault tolerant computing; programming; N-version programming; N-version software; consistent comparison problem; decisions; finite-precision calculations; finite-precision numbers; Aircraft; Application software; Arithmetic; Computer science; Fault tolerance; Large-scale systems; NASA; Pressure measurement; Software reliability; Temperature sensors;

fLanguage

English

Journal_Title

Software Engineering, IEEE Transactions on

Publisher

ieee

ISSN

0098-5589

Type

jour

DOI

10.1109/32.41339

Filename

41339