[RC5]V3...Lets beat the GIMPS effort

Kevin Postlewaite kpost at best.com
Tue Aug 18 17:44:57 EDT 1998

> But considering the d.net website and sheer amount of users participating, I
> think that a lot of participants who are currently participating in GIMPS or
> both GIMPS and d.net will switch over to one solid d.net core.  Why worry
> about having two different clients to install(some on some machines and some
> on others) when they could just install one client on all machines.

If d.net can create a core that rivals the performance of Woltman's
program, it would be impressive.  But no one else has accomplished this

> Also, another issue is that with Mersenne primes, factoring will still need
> to be done.  The problem is that there won't be any 'glory' in factoring.
> Who wants to work to make it easier for someone else to find a new prime
> number when they could have just dedicated their machine to finding the
> prime number themselves.  So, I think that perhaps d.net should force this
> on people.  Basically you HAVE to do some factoring, like it won't allocate
> you a new part of a prime to check until you accomplish a certain block of
> factoring.  

Given that it takes so much less effort to factor a number than run a
Lucas Lehmer test (the algorithm used by GIMPS), only a small proportion
of machines need to factor.  In GIMPS, there's actually MORE factoring
being done than needed- the factoring effort is zooming ahead of the LL
testing.  Thus, I don't think it's necessary to mandate factoring for this
reason. (in fact, GIMPS can probably handle the factoring for d.net in
addition to GIMPS' own needs if necessary)  OTOH, anything less than a
Pentium really can't do LL testing, so they should be required to do
factoring anyway, or else stick with RC5.
> Another issue is well, how will this work.  My P2-266 can crunch a prime
> number in about 2 weeks.  Now, I know that's going to be unappealing to
> people and hopefully d.net will break that up into smaller chunks.  But, if
> this happens and a new prime is discovered then who would get credit?  Will
> the new stats box keep track of all email addresses that worked on a number
> or will the credit just be given to "The Users of d.Net"?

Actually this is not an issue since the Lucas Lehmer testing cannot be
split up in any useful way to speed up an individual exponent's being
tested. Each step of the algorithm run on a specific exponent requires the
output of the previous step, so it cannot be parallelized.  It is possible
to move the SAVE file from one machine to another in case a machine drops
out and submits this file, but as it exceeds 1 MB, this won't usually be
done except locally.

What I don't understand is why d.net isn't attacking Certicom's
challenges, or RSA's factoring challenges.  But please help us find the
next Mersenne Prime!

Kevin Postlewaite

To unsubscribe, send 'unsubscribe rc5' to majordomo at lists.distributed.net
rc5-digest subscribers replace rc5 with rc5-digest

More information about the rc5 mailing list