From: Lucas Wiman <[EMAIL PROTECTED]>
Subject: RE: Mersenne: Multiple residues - enhancing double-checking
To: [EMAIL PROTECTED]
Date sent: Wed, 4 Aug 1999 19:19:56 -0400 (EDT)
>
> >Double-Check:
> >M23780981,64,863FF87,678676AA,FF637BC,[...],CRC:9923FDA.
>
> This scheme makes almost no sense for normal double checking. This is becuase
> it would save *no* time at all. Think about it, even if you identify that an
> error ocurred in the second week of a 3-month test,
The errors can occur with the same probability during de
double-check. So, when a mismatch is found, the double-check
stops this exponent and a triple check is started on another
computer (hopefully with another program). The triple check
decides who is wrong. If the double check were wrong you saved a
partial LLTest. If the first check is wrong, the double check
continues just when it stopped, this time as a first time check. In
any case, the triple check turns to be a double check.
Check it ! :-)
After all, maybe the major advantage of all this is the
ability to catch bugs early, when some people volunteers to run
simultaneous LLTests with different programs. As time passes, the
coordinator can compare results quickly. Note that some bugs can
be very subtle. Nothing replaces the testing on the field. I would
like to know how George notified the v17 bug.
> you still have to run it
> to completion, and a third test must also be run. (So 3 LL tests must still
> be run if an error ocurrs).
Correct.
> > This schema makes possible simultaneous checking,
> > though. But the start-stop mechanism you describe has little
> > sense.
Sorry, I mean "has little sense given the individualism of
certain GIMPS members". A lot of people says "It's _my_
exponent. Dare to work on it before I finish !" Practical or not, I
respect this attitude.
Saludos
Oscar Fuentes
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