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From: Kilgallen@SpamCop.net (Larry Kilgallen)
Newsgroups: comp.lang.ada
Subject: Re: Ariane Failure
Date: 11 Apr 2002 09:33:17 -0500
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In article <a93uj0$1be$1@news1.xs4all.nl>, fdebruin@xs3.xs4all.nl (fdebruin) writes:

> For example, in the case of Ariane 501 the IRS software in the two units
> could have been developed indepently by two different companies. Maybe
> the problem would have occurred in only one of them.
> 
> This will immediately raise the issue of deciding which software is 
> roviding you the correct data, in case they differ. This will lead to
> some kind of arbitrator (a new single point of failure) or a third
> software package to allow majority voting.
> 
> You will easily tripple the cost of your software. In addition, I am not
> convinced that the added robustness makes up for the added complexity.
> Furthemore, you are still not fully covered because your software
> specification might contain an error that will be common to all indepently
> developed software.

Just have each implementation use a different specification :-)