On Tuesday 24 September 2002 06:05, Daran wrote: > P-1, like any other GCD-based factorisation method, will yield a composite > result in the event that there are two (or more) prime factors within its > search space. It seems unlikely that this would happen in practice because > unless both were > ~ 64 bits, one of them would most likely have been found > earlier during TF. However given that some factors found have been > 130 > bits,
TTBOMK only using ECM - and those events are rare enough to be newsworthy. I don't think P-1 has found a "proper" factor exceeding 110 bits, yet. > then the possibility is there. > > I was wondering if returned factors are checked for primality. I've found a few composite factors whilst running P-1 on small exponents. They've all factorised _very_ easily (well within one minute) using "standard tools". Basically I'm interested enough to do this myself whenever what appears to be an abnormally large factor is found, but it wouldn't be hard to automate. Also very large factors are found at a low enough rate that there's simply no need to distribute the checking. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
