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 2012-03-12, 02:22 #1 137ben   Mar 2012 716 Posts What about double-checking TF/P-1? While it is possible for an error in a TF to "miss" a found factor, it probably isn't worth the effort to double check. However, it may well be worth checking that found factors are actually factors, to be sure that we don't miss any Mersenne primes. It would be a lot easier that the initial round of trial factoring, because we would only need to check TF assignments for which a found factor was reported. Since this is relatively rare, (and in fact, TF jobs in which factors are found tend to take much less time than those which find no factors), it shouldn't take very much effort to do, and it helps ensure that we do not miss any primes. So, anyone else think this is a good idea?
 2012-03-12, 04:18 #2 LaurV Romulan Interpreter     Jun 2011 Thailand 9,161 Posts There is NO EFFORT needed to check a factor. The process is straight forward and it is done automatically by the server. Imagine you want to factor 123509 using only pencil and paper, it will take you a while and your only perspective would be to check all primes below 350 or so, but if I tell you that 113 is a factor, you will not need more then few seconds to say if that is true or not. Checking if some x is a factor of some y need no effort. The problem is that these possible x-es are sooooo many, and we have difficulties to "choose" the right one...
 2012-03-12, 04:50 #3 Xyzzy     "Mike" Aug 2002 11111000010102 Posts An old thread: http://www.mersenneforum.org/showthread.php?t=1085
2012-03-12, 22:14   #4
Mini-Geek
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"Tim Sorbera"
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Quote:
 Originally Posted by LaurV There is NO EFFORT needed to check a factor.
To be technically correct: The effort needed to check a factor [of a typical Mersenne number GIMPS handles] is trivial, but not zero.

Last fiddled with by Mini-Geek on 2012-03-12 at 22:15

 2012-03-12, 22:26 #5 davieddy     "Lucan" Dec 2006 England 2·3·13·83 Posts Is this Pussy Heaven? Not Roy Orbison or Dennis Hopper David Or even this: Mr Sandman Even Homer nods Last fiddled with by davieddy on 2012-03-12 at 22:34
2012-03-13, 00:11   #6
Uncwilly
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23FF16 Posts

Quote:
 Originally Posted by Mini-Geek To be technically correct: The effort needed to check a factor [of a typical Mersenne number GIMPS handles] is trivial, but not zero.
Vanishingly small, might be a better term.

 2012-03-13, 04:01 #7 Christenson     Dec 2010 Monticello 111000000112 Posts How about the amount of computational effort to check a found factor is on the same order of effort as transmitting it over the internet and receiving it at the server.

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