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From: Kilgallen@SpamCop.net (Larry Kilgallen)
Newsgroups: comp.lang.ada
Subject: Re: n versioning is there any other better approach
Date: 22 Apr 2006 06:50:23 -0500
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In article <25f2g.111486$oL.37868@attbi_s71>, "Jeffrey R. Carter" <spam.not.jrcarter@acm.not.spam.org> writes:
> Robert A Duff wrote:
>> 
>> Multiple versions can certainly help, but it doesn't help nearly as much
>> as one would like.  It sure would be nice if, given a probability P of
>> error, N versions would make it P**N.  With software, it's not that
>> good, because my errors are not independent of your errors, because our
>> brains think alike to some extent.
> 
> I saw a study once that indicated that multiple versions tend to have 
> similar errors.

Do you recall whether there was any commonality in the versions, other
than the specification ?   Like language, background of implementers,
deadline, etc. ?