20181210, 14:30  #34 
"Carlos Pinho"
Oct 2011
Milton Keynes, UK
2×2,357 Posts 

20181210, 14:48  #35  
Sep 2003
2^{2}·3·5·43 Posts 
Quote:
However, it might be worthwhile to retest every known Mersenne prime with PRP. Currently our verification method is to use different software implementations of the same LucasLehmer algorithm on different hardware (GPU vs CPU). PRP, on the other hand, is a different algorithm. No, it can't prove primality. But it can prove compositeness. And at this point, with such an improbable surplus of Mersenne primes, maybe a drastic sanity check is needed for peace of mind, just in case software implementers exchanged ideas and somehow ended up all making some identical implementation error. It's a crazy notion, I know. 

20181210, 15:07  #36  
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
1164_{16} Posts 
Quote:
Last fiddled with by kriesel on 20181210 at 15:29 

20181210, 15:19  #37 
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
2^{2}·3·7·53 Posts 

20181210, 15:26  #38 
6809 > 6502
"""""""""""""""""""
Aug 2003
101×103 Posts
8,627 Posts 
I've noticed some interesting names with some interesting exponent assignments that will be "home for the holidays" as it were.
MD5 hash guess of one that looks tasty (includes exponent assignee MM/DD expected completion date) 227a10ba5bbe1b4b033c2983ee417ee9 It does fit the 2 requirements posted by George and Alex. There also appears to be some funny business in the history on the assignment page. Last fiddled with by Uncwilly on 20181210 at 15:28 
20181210, 15:50  #39 
Serpentine Vermin Jar
Jul 2014
CCA_{16} Posts 
The first verification run done by ATH confirms it: We have a new prime!
I'm not sure when George will do the press release  as was pointed out, the best way to predict when a prime is found is when George is on vacation. I'll say a few things:

20181210, 16:14  #40 
Sep 2018
1000101_{2} Posts 
So just to be sure, I set the lion's share of my machines to PRP. Should they be doing LL instead, or is PRP fine?

20181210, 16:23  #41 
P90 years forever!
Aug 2002
Yeehaw, FL
5·1,433 Posts 

20181210, 17:31  #42  
Serpentine Vermin Jar
Jul 2014
2×1,637 Posts 
Quote:
Here's my understanding: PRP is probabilistic and LL is deterministic. So although a PRP can say "M###" is probably prime, an LL test can say "M###" is prime. PRP tests have the benefit of the Gerbicz error checking code that may make doublechecking the tests unnecessary. As to just how probable the PRP tests are, I understand that when PRP says it's probably prime, that probability is VERY high. And when I say the PRP error checking makes doublechecks obsolete, I think that's generally true although I foresee cases where spotchecks make sense, but overall that's where I think it's headed. If I'm wrong in my assumptions, someone will correct me I'm sure. When it comes to finding a new Mersenne Prime, I guess the question about whether a probable finding is good enough to be accepted, or would the LL test be required before it's confirmed. Maybe that's similar to how we already verify a prime using different software  it's a way of ensuring there aren't any code issues or other obscure things. 

20181210, 17:55  #43 
Serpentine Vermin Jar
Jul 2014
2·1,637 Posts 
The mersenne.org homepage has been updated with a little blurb about the discovery, linking to this thread. More of a prerelease release with a promise of details to follow.

20181210, 18:28  #44  
"TF79LL86GIMPS96gpu17"
Mar 2017
US midwest
2^{2}·3·7·53 Posts 
PRP and other runs on alreadyknown mersenne primes
Quote:
https://www.mersenne.org/report_expo...exp_hi=&full=1 https://www.mersenne.org/report_expo...exp_hi=&full=1 https://www.mersenne.org/report_expo...exp_hi=&full=1 Quite a few Mersenne primes also have recent failed TF or P1 attempts also. These following PRP runs on already known mersenne primes have not been reported yet to mersenne.org, but could be if it were useful. I may assemble them into my gpuowl reference data instead or also. Running known mersenne prime PRP checks was done as QA on gpuowl new versions/features. gpuowl v5.0df2bdf2 build for Win7 x64 PRP with P1, p= 216091, 756839, 859433 by kriesel https://www.mersenneforum.org/showpo...&postcount=867 Per Preda, for a prime, residue = PRP1 base, see https://www.mersenneforum.org/showpo...&postcount=826 https://www.mersenneforum.org/showpo...&postcount=823 gpuowl v3.891c52fa p=1257787 https://www.mersenneforum.org/showpo...&postcount=827 (p=756839, example of PRP GEC in https://www.mersenneforum.org/showpo...&postcount=815) gpuowl v5.0f604bb1 p=1257787, 1398269, 2976221, 3021377 by kriesel https://www.mersenneforum.org/showpo...&postcount=818 Also, unposted(?), gpuowl v5.09c13870 p=6972593 Last fiddled with by kriesel on 20181210 at 18:48 

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