----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, December 04, 2001 2:38 AM Subject: Re: Mersenne: Re: Factoring benefit/cost ratio
> > and one that is decades (at least) behind GIMPS. The only reason we > > do any factoring at all is to reduce the time spent on LL testing. > > But if factoring is not really part of GIMPS's purpose (and I agree it > isn't), how can a separate factoring effort be "behind" GIMPS at all? > Aren't they measuring their progress in a different, non-comparable, > dimension? Say rather that there are various criteria by which the two projects can be compared. It's probably true that it would take them decades or more to completely factor a set of prime exponents comparable to those which GIMPS has verified composite. (and that's ignoring the effort to factorise the cofactors of Mersennes with composite exponents). They're probably not that far behind GIMPS in terms of total computing done. How far will depend upon how good they are at mobilising support. [...] > In reply to a statement of mine about "the extra benefit of finding a > specific factor", > Daran G. wrote: > >I can see no way of objectively quantifying this benefit. > > Well -- if there's no objective quantification of the extra benefit of > finding a specific factor, then it seems to me that there's no > objectively quantifiable justification for saying that it's not > valuable to do a certain amount of "extra" P-1 factoring on a > once-LL'd Mnumber. :) Can't argue with that. [...] > Daran G. wrote: > >It seems to be implicitely acknowledged in the way the trial > factoring > >depths are determined. > > But don't forget that this refers to a depth determined by Prime95 > _in the context of calculating the factoring tradeoff point for > maximizing GIMPS throughput for the "Test=" worktype_, NOT the context > of a "Factor=" or "Pminus1=" worktype where the user has explicitly > specified factoring limits, possibly for reasons beyond the ken of > Prime95. That seemed to be the question you were asking. [...] > I'm not saying that Prime95 should incorporate into its calculations a > nonzero value for the benefit of finding a specific factor. > > I'm saying that it is rational for someone to decide to factor past > the Prime95-calculated tradeoff points, and that it is unjustified to > criticize "extra" factoring on the grounds that going past the > Prime95-calculated tradeoff points is wasted effort. I agree. But you can look at this in terms of an even greater project than GIMPS - The Great Distributed Computing Project that encompasses all such efforts, and aims to use spare computing cycles to increase the knowledge base of humankind generally. What contribution one chooses to make depends upon ones own personal preferences. > Richard B. Woods Daran G. _________________________________________________________________________ Unsubscribe & list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
