Mersenne Digest Friday, October 5 2001 Volume 01 : Number 889 ---------------------------------------------------------------------- Date: Wed, 3 Oct 2001 02:30:10 -0400 From: "Carleton Garrison" Subject: Re: FW: Mersenne: Re: Factoring Failure? > At 04:07 PM 9/30/2001 -0700, Daniel Swanson wrote: > >I went through the Cleared Exponents > >report looking for other examples of factors found during > double-checks that > >should have been found during the initial factorization. > > 5977297 53 DF 6726544627832489 > > 6019603 57 DF 137024179940485697 > > 7019297 57 DF 160100125459121849 > > 7020641 58 DF 226230108157229263 > > 7025987 56 DF 74052063365823791 > > 7027303 55 DF 31090234297428433 > >10159613 56 DF 68279769831982367 > >Were numbers in this range all originally factored by the same user > >or computer? > Either way, GIMPS > has never considered missing a factor as a big deal. It only means > some wasted effort running a LL test that could have been avoided. I wonder if by using configuration settings, people are able to skip as many, if not all, factoring stages? I believe the idea of trying to skip P-1 factoring was talked about within the last 3 or 4 months. Apparently there are people who would just prefer to get credit for doing LL work than to find factors. Until factoring time (while one is LL testing) is at credited at the same same rate as LL testing, let alone getting credited not at all (most of the time no factors are found), results like the above could become common place. _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Wed, 3 Oct 2001 02:41:27 -0500 (CDT) From: ribwoods@execpc.com Subject: Mersenne: Re: Factoring Failure? Daniel Swanson wrote: > 5977297 53 DF 6726544627832489 > 6019603 57 DF 137024179940485697 > 7019297 57 DF 160100125459121849 > 7020641 58 DF 226230108157229263 > 7025987 56 DF 74052063365823791 > 7027303 55 DF 31090234297428433 >10159613 56 DF 68279769831982367 I'm pretty sure the second column is the previous trial-factoring limit, in units of power-of-2. For M7019297, the found factor 160100125459121849 is larger than 2^57 (= 144115188075855872), and for M7025987, factor 74052063365823791 is greater than 2^56 (= 72057594037927936). Unless I'm misinterpreting something, those two cases don't indicate a trial-factoring failure. _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Wed, 3 Oct 2001 12:40:29 -0400 From: "Carleton Garrison" Subject: Re: FW: Mersenne: Re: Factoring Failure? > > I believe the idea of trying to skip P-1 factoring was talked about within > > the last 3 or 4 months. Apparently there are people who would just prefer > > to get credit for doing LL work than to find factors. > > This is why I like that you loose credit for a LL-test if someone else > finds a factor later, or if two other independant checks prove your > result to be wrong. Me too. I understand that George's top producer page does this, while the PrimeNet stat page does not. PrimeNet really needs this capability. Carleton Garrison LL#163 F#295 G#253 www.teamprimerib.com _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Wed, 03 Oct 2001 18:29:52 -0700 From: Gerry Snyder Subject: Re: FW: Mersenne: Re: Factoring Failure? Carleton Garrison wrote: > > [? wrote:] > > > > This is why I like that you lose credit for a LL-test if someone else > > finds a factor later, or if two other independant checks prove your > > result to be wrong. > > Me too. I understand that George's top producer page does this, while the > PrimeNet stat page does not. PrimeNet really needs this capability. To me, there is no question that an LL test that is shown to be wrong should not count for anything. The number still required two more LL tests, so that it as if the erroneous one had not been done. But, at least in theory, every Mersenne number proven non-prime will eventually be factored. Again, to me, so what? At least the LL test showed that further factoring activity would eventually succeed. I have nothing against George doing things that way. (When I play ball with him, I play by his rules or I don't play at all. You know why? Because it's his ball, that's why.) Seriously, I can see some point to doing things that way, but I would do probably do it differently. But even more seriously, I'm just glad to be in the game, and I am grateful to George and all the others who have made it easy and fun to participate. Gerry PS I just got a chuckle from imagining a very competitive team tearing down an opponent by finding what numbers the opponent had done LL tests on, and factoring them. _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Wed, 03 Oct 2001 18:50:21 -0700 From: Eric Hahn Subject: Mersenne: Re: MERSENNE: Factoring Failure? Steve Harris wrote: >-----Original Message----- >From: bjb@bbhvig.uklinux.net >To: mersenne@base.com >Date: Tuesday, October 02, 2001 3:44 PM >Subject: Re: FW: Mersenne: Re: Factoring Failure? > > >> > Either way, GIMPS >> > has never considered missing a factor as a big deal. It >> > only means some wasted effort running a LL test that could >> > have been avoided. > >>True enough - though I'm concerned that the "no factors below 2^N" >>database may be seriously flawed, from the point of view of GIMPS >>it would seem to be a waste of time to go round redoing trial >>factoring just to fix this problem. > >Yes, from the point of view of GIMPS (that is, searching for >Mersenne primes) it's not a huge deal... but there also exists >an effort to fully factor the candidates that are not prime, >and this throws a big problem into that project. Someone could >be trial factoring an exponent from 2^59 to 2^65 and find a >factor in that range after a smaller factor had been missed, >and it will go into the database as the smallest factor when >it actually is not. Might be decades before the smaller factor >is discovered. Actually... IIRC... George noted once that the database of smallest KNOWN factors was just that... and did NOT necessarily mean that it contained the smallest factors of any given exponent... There was a bug in a previous version (v19??) which caused Prime95 to not continue trial-factoring to find a smaller factor after one had been found and it had been stopped (or went to sleep)... There was also the advent of P-1 factoring which does not necessarily find the smallest factor, but instead finds factors comprised of lots of small factors, and can therefore miss smaller factors which does not have lots of small factors... In this case... the database would not necessarily have the smallest factor for every exponent with a factor found... but instead the smallest KNOWN factor... which is not necessarily the smallest factor for that exponent... Eric _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Wed, 3 Oct 2001 21:09:48 -0700 From: "Daniel Swanson" Subject: Mersenne: Re: Factoring Failure? Jean-Yves: Did you check to see if any or all of the exponents cleared by "tomfakes" matches with the exponents I found in the 701xxxx-702xxxx range? List: Three new small factors have been turned in in the past few days. The list in the 70xxxxx range is now 7019297 57 DF 160100125459121849 27-Sep-01 22:52 TempleU-DI TD01489_Cub1 7020641 58 DF 226230108157229263 30-Sep-01 02:05 RayPelzer Homebase 7025987 56 DF 74052063365823791 30-Sep-01 01:12 shaneamy P600A 7027303 55 DF 31090234297428433 30-Sep-01 22:14 dswanson nosnawsd 7028947 58 DF 203918491658210359 01-Oct-01 03:11 SW jobn164 7033963 56 DF 100945633281264553 03-Oct-01 07:36 TempleU-DI DellGXaGhost 7036409 58 DF 321885922408857601 04-Oct-01 02:54 MartinTraupe Maxsein Dan > -----Original Message----- > Date: Mon, 1 Oct 2001 22:23:38 +0200 > From: "Jean-Yves Canart" > Subject: FW: Mersenne: Re: Factoring Failure? > > Hello all, > > I have browsed some logs I archived long time ago and I have found this: > > In may 1998, one user, "tomfakes", cleared around 80 exponents with factor > found = "1" > It was in the range 7013000-7055000. > > Regards, > > Jean-Yves _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 04 Oct 2001 01:44:53 -0400 From: Nathan Russell Subject: Re: FW: Mersenne: Re: Factoring Failure? On Wed, 03 Oct 2001 18:29:52 -0700, Gerry Snyder wrote: >But, at least in theory, every Mersenne number proven non-prime will >eventually be factored. Again, to me, so what? At least the LL test >showed that further factoring activity would eventually succeed. It might be pointed out that we are still finding factors of numbers in the same size range as some found to be prime in the 1950's, and that it may well be (due to such things as the uncertainity principle, the speed of light, and the need to not have to worry about whether there actually is an electron crossing a closed switch when one ought to) impossible to factor some of the numbers now being tested. Right now, it's well under an hour's work to prove *any* 700 digit number prime, but factoring general numbers of the same size in an hour would be a very good way to get very rich (legally or otherwise) very quickly. >PS I just got a chuckle from imagining a very competitive team tearing >down an opponent by finding what numbers the opponent had done LL tests >on, and factoring them. If things are being done properly, they should be better off by far doing their own tests, since the factoring bounds are chosen to stop when it's no longer worthwhile to continue factoring in hopes of averting both the first and second tests. Nathan _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 04 Oct 2001 01:52:32 -0400 From: Nathan Russell Subject: Re: FW: Mersenne: Re: Factoring Failure? On Tue, 2 Oct 2001 19:52:42 -0000, bjb@bbhvig.uklinux.net wrote: >However if it could be established that all the "missed" factors >reported were the work of one user, perhaps it would be worth fixing >the database to force rerunning of trial factoring for those factoring >assignments run by that user when the exponents are reassigned >for double checking (or LL testing). Given the scale of the bad results (probably a fair bit over 60 exponents, at a rough guess), if I were king, I would just block the responsible user until I got a reasonable exponent. Many of the numbers listed in the original post, however, are already behind the "main front" of double-checking. Of course, we would only expect to be finding those that are, but I'd guess no more than 200-300 exponents are involved (and likely less). If it was a computer error of some sort, I wouldn't expect to see that many errors. That said, I vaguely recall reading somewhere that some versions of Windows always give the same memory range to the same program (the context was that what appears to be an error in a given program may cause major general problems under Linux). If that is the case, is it possible that every time Prime95 on a given system started up its executable was loaded on top of a bad range of memory in just such a way as to make it impossible to find a factor (say, by changing the expected output of the function when one is found). This is speculation on my part, of course, but I think it's worth mentioning.... Nathan _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 4 Oct 2001 18:30:41 -0000 From: bjb@bbhvig.uklinux.net Subject: Re: FW: Mersenne: Re: Factoring Failure? On 3 Oct 2001, at 18:29, Gerry Snyder wrote: > To me, there is no question that an LL test that is shown to be wrong > should not count for anything. The number still required two more LL > tests, so that it as if the erroneous one had not been done. The counter-argument is that work submitted _in good faith_ should be credited. However I quite agree that there is a nice judgement here in how much "good faith" there is in users submitting results from systems which are known to have serious hardware stability issues. > > But, at least in theory, every Mersenne number proven non-prime will > eventually be factored. Again, to me, so what? At least the LL test > showed that further factoring activity would eventually succeed. Might be a while, though... look at the effort needed to factor M727 - finally succeeding about half a century after the determination of compositeness, despite huge advances in mathematical techniques and raw computational power. > > I have nothing against George doing things that way. (When I play ball > with him, I play by his rules or I don't play at all. You know why? > Because it's his ball, that's why.) Seriously, I can see some point to > doing things that way, but I would do probably do it differently. > > But even more seriously, I'm just glad to be in the game, and I am > grateful to George and all the others who have made it easy and fun to > participate. Precisely. > > PS I just got a chuckle from imagining a very competitive team > tearing down an opponent by finding what numbers the opponent had done > LL tests on, and factoring them. I suspect that finding enough of those factors would cost the "very competitive team" much more effort than it would to overtake the opponent by applying their resources to running LL tests. If not, we don't do enough factoring before proceeding to LL testing. If you really want an insight into "competitiveness", just look at what goes on in projects like RC5. Unauthorized use of systems appears to be fairly common, as are counter-accusations of this activity. Denial-of-service attacks on networks hosting systems run by competitors are not unknown. Extreme overclocking to the point of serious instability appears to be almost "de rigeur" (except on systems "borrowed" from other users!). Personally I would far prefer not to have league tables at all because they do tend to encourage these sorts of antisocial behaviour, though I do accept that they can and do also encourage legitimate users to "try harder". The effort people like me put in to trying to find factors of "small" Mersenne numbers is _for fun_ - an effective way of using resources which are not suitable for LL testing for one reason or another. Given the tiny credit for running LL tests on small exponents, any damage to individual users' ratings in George's tables is likely to be imperceptible. Finally, and here's the point: though, from the point of view of someone trying to find first factors, it doesn't matter whether a known factor is actually the smallest, it _is_ highly desirable that the database of previous unsuccessful factoring effort is _reasonably_ accurate. Finding a "missed" small factor using an advanced technique may or may not be successful, but it's an expensive way of doing the job. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 4 Oct 2001 21:00:40 +0200 From: Guillermo Ballester Valor Subject: Re: Mersenne: Glucas2.8b - test crash Hi, a bit late but now I realize I still have not replied this to the list. This thread has been discused in private e-mails. > hi folks > i builded glucas 2.8b and then tested. > during test huge always in test # 24 it crashes - segmentation > fault. > when i run test 24 alone it pass it fine. > This was a strange bug not affecting other than openbsd OS, and in some rare circumstances. When Glucas was finishing a job (an exponent or a short test) it does not free the main array in the right moment, so it could be two big arrays allocated in a moment and spend all the allowable memory. Gregory only had managed 64Mb of memory for Glucas and it crashed in huge selftest, but no in alone selftest . The Glucas's users don't have to worry about this problem unless they are checking more than 40M exponents in a limited memory system. I can send a patch to these users by request. I will release the patch, and a new version 2.8c in few days. Of course, like new Mlucas versions, there will be some improvements. The most remarkable feature is for Itanium binaries, It almost doubles the speed from 2.8b to 2.8c. Now, Itanium will be the fastest platform for Glucas (in performance/clock). Regards. Guillermo - -- Guillermo Ballester Valor gbv@oxixares.com Granada (Spain) _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Fri, 5 Oct 2001 17:36:14 -0400 From: "Digital Concepts" Subject: Mersenne: What are the PrimeNet formulas for calculating LL and Factoring credit? This is a multi-part message in MIME format. - ------=_NextPart_000_02A6_01C14DC4.3B0A3CE0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable First a short memory recollection... A few months back I wrote in = explaining that I wanted to compare contributions (work done in CPU = years) between clients running under a team umbrella. I was privately = replied to and referred to the benchmark page as the way they would do = it. More recently, someone asked the same thing and I believe George = referred them to the status page. I've done it both ways and they come = out very close, but I assume the status page is the one that is going to = be kept current as new releases and timings come along, and the one = George uses. Either time though, it was mentioned how difficult it was to calculate = factoring years, and I see why. Yet there must be a formula. Who here = is a PrimeNet rep? With this info, maybe someone might volunteer a calculator page, where = someone could enter an exponent and get the LL value, and optionally = whatever criteria is stored in factoring messages to PrimeNet, to = determine the Factoring value. Thanks for you consideration, Carleton Garrison LL#164 F#291 G#253 www.teamprimerib.com - ------=_NextPart_000_02A6_01C14DC4.3B0A3CE0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
First a short memory = recollection... =20 A few months back I wrote in explaining that I wanted=20 to compare contributions (work done in CPU years) = between clients=20 running under a team umbrella.  I was privately replied = to and=20 referred to the benchmark page as the way they would do = it.  More=20 recently, someone asked the same thing and I believe George = referred=20 them to the status page.  I've done it both ways and = they come=20 out very close, but I assume the status page is the one that is = going to be=20 kept current as new releases and timings come along, and the one George=20 uses.
 
Either time though, it was mentioned = how difficult=20 it was to calculate factoring years, and I see why.  Yet there must = be a=20 formula.  Who here is a PrimeNet rep?
 
With this info, maybe = someone might=20 volunteer a calculator page, where someone could enter an exponent and = get the=20 LL value, and optionally whatever criteria is stored in factoring = messages to=20 PrimeNet, to determine the Factoring value.
 
Thanks for you = consideration,
Carleton Garrison  LL#164 F#291 G#253  www.teamprimerib.com
- ------=_NextPart_000_02A6_01C14DC4.3B0A3CE0-- _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ End of Mersenne Digest V1 #889 ******************************