N-version programming

"N"-version programming (NVP), also known as multiversion programming or multiple-version dissimilar software, is a method or process in software engineering where multiple functionally equivalent programs are independently generated from the same initial specifications. The concept of "N"-version programming was introduced in 1977 by Liming Chen and Algirdas Avizienis with the central conjecture that the "independence of programming efforts will greatly reduce the probability of identical software faults occurring in two or more versions of the program". The aim of NVP is to improve the reliability of software operation by building in fault tolerance or redundancy.
NVP approach.
The general steps of "N"-version programming are:
Applications.
"N"-version programming has been applied to software in switching trains, performing flight control computations on modern airliners, electronic voting (the SAVE System), and the detection of zero-day exploits, among other uses.