Mersenne Digest Monday, May 14 2001 Volume 01 : Number 850 ---------------------------------------------------------------------- Date: Sun, 13 May 2001 11:03:50 +0200 From: mohk <[EMAIL PROTECTED]> Subject: Re: Mersenne: Pentium 4 owners - pre-beta prime95 release available At 03:02 13.05.2001, you wrote: >Hi, > > The P4-optimized version of prime95 is ready for adventurous users >to try out. Ordinarily I would not release a trial version at this point, >but I'm sure >P4 owners are itching for a 3x performance boost. > > If you do not own a P4, then DO NOT DOWNLOAD THIS VERSION. >It contains no new features and your results will be marked invalid if we >later discover a bug in this code. Don't you say, this code enhances the Athlon as well? regards, Mohk _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 13 May 2001 12:13:28 +0200 From: "Steinar H. Gunderson" <[EMAIL PROTECTED]> Subject: Mersenne: Re: Pentium 4 owners - pre-beta prime95 release available On Sun, May 13, 2001 at 11:03:50AM +0200, mohk wrote: >Don't you say, this code enhances the Athlon as well? No, it doesn't. It's that much faster mainly because it utilizes the SSE2 instructions that are new on the P4, which the Athlon doesn't have (yet). /* Steinar */ - -- Homepage: http://members.xoom.com/sneeze/ _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 13 May 2001 11:48:48 -0000 From: "Brian J. Beesley" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Pentium 4 owners - pre-beta prime95 release available On 12 May 2001, at 21:02, George Woltman wrote: > If you try out this version, please let me know of any problems. It would > be helpful if you ran double-check assignments for a few weeks. If anyone wants to be a bit more adventurous than taking "ordinary" PrimeNet DC assignments, I have a limited number of exponents which will require double-checking at some stage for which interim residues at 1 million iteration checkpoints are available. The point here is that if you also set the program for million iteration checkpoints (InterimFiles=1000000 in prime.ini) you will be able to catch any discrepancies early without having to continue the run to the end. (Of course there is a chance that my checkpoint residues may not be correct - but the systems they are running on seem to be pretty reliable!) The exponents for which I have interim residues are as follows: 7056503, 7092307, 7094839, 7477177, 7731131, 7731259, 7871953, 7927697, 7979819, 8164349, 8167919, 8242327, 8255881, 8369941, 8380621, 8434523, 8549371, 8555881, 8563109, 8573107, 8615273, 8650927, 8655991, 8715337, 8719367, 8767471, 8900161, 8907359, 9057403, 9117209, 9189533, 9443311, 9475097, 9607691, 9617929, 9743639, 9743803, 10068077, 10126621, 10319891, 10386067, 10809893, 11173153, 11561909, 11570227, 11636479, 11772809, 12141223 & 12450397. If anyone is interested in testing any of these with the P4 code, let me know around what size exponent you're willing to take on; I'll reply by email allocating a unique exponent with a list of the appropriate million iteration interim residues. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 13 May 2001 11:57:41 -0500 (CDT) From: [EMAIL PROTECTED] Subject: Mersenne: Re: story of scientists travelling by train Brian J. Beesley wrote: > > Mathematician (after long pause): "No, in Scotland there exists at > least one sheep, at least one side of which appears to be black." What do you mean, "long pause" ??? :-) Richard Woods _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 13 May 2001 12:10:38 -0500 (CDT) From: [EMAIL PROTECTED] Subject: Mersenne: Re: story of scientists travelling by train Brian J. Beesley wrote: > > As the train crosses the border into Scotland, they observe a > black sheep in an otherwise empty field. (* snip *) Mathematician #2 (after reading story): "Does that mean that the black sheep is both the additive and the multiplicative identity?" :-) Richard Woods _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 13 May 2001 19:41:31 -0400 From: Nathan Russell <[EMAIL PROTECTED]> Subject: Re: Mersenne: missing exponents? On Sat, 12 May 2001 16:38:47 -0400, Jud McCranie wrote: >At 08:14 PM 5/12/2001 +0000, Brian J. Beesley wrote: > >rather small, so the reason a third or fourth run is neccessary is >>very probably because results with mismatching residuals are being >>submitted for some reason. Most probably random glitches? > >Another nice thing would be if people who have submitted several results >that don't match other people's results they could be notified that they >may have a hardware problem. I can't help wondering whether some users would find that to be overly invasive or startling; however, if I had such a problem - especially one that could cause slow thermal damage - I would want to know about it. I deal with altogether too many people on other mailing lists and newsgroups who believe that it is normal for their machine to take two attempts to make it through a 25-minute kernel upgrade. Granted, a 5-week GIMPS run is a more stringent criterion, but AFAIK most machines /should/ be able to survive without more than 1-2 errors a year (I've had two since I started last January). Nathan _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 13 May 2001 19:46:48 -0400 From: Nathan Russell <[EMAIL PROTECTED]> Subject: Re: Mersenne: missing exponents? On Sat, 12 May 2001 10:22:06 -0400, George Woltman wrote: >Why did this affect the server's counts? Well, that's a long story. It has to >do with design decisions (compromises actually) made at Primenet's inception. >Primenet's database is a subset of the master database which I maintain >3000 miles away from the server. In an ideal world there would only be one >database maintained by the server and all database maintenance (like >triple-checks) would be handled automatically. As it stands, I notice that PrimeNet is given assignments only a few tens of thousand of exponents in advance. Is this done so that you have more flexibility, or is it a technical issue with the number of exponents the server can handle? Nathan _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 13 May 2001 20:06:31 EDT From: [EMAIL PROTECTED] Subject: Mersenne: Re: games one can play with genuine composites Brian Beesley wrote: > If someone could merely demonstrate that, if the smallest factor of > c = 2^p-1 is 2kp+1 for some k, C = 2^c-1 and the smallest factor of > C with the form 2Kc+1 is 2Kc+1 for some K, then K > k^x for some > x > 0, this would show that searching for factors of C without > knowledge of factors of c is probably _unlikely_ to be successful. True, for composite c, not all factors of 2^c - 1 need have form 2.K.c + 1; for example, if c = 15, 2^c - 1 = 7.31.151, and the smallest factor, 7, does not have the form 2.K.15 + 1. However, if we do not know any of the factors of c, the best we can reasonably do is to search for factors of the form 2.K.c + 1, which we can do without knowing any of the factors of c. For c sufficiently large, even sieving for factors of this form becomes prohibitively expensive - take your own favorite composite lacking known factors, c = 2^33219281-1. Checking if the smallest eligible candidate factor 2.K.c + 1 divides C = 2^c - 1 would need roughly 33219281 squarings modulo the candidate factor, and since that is not of special form (e.g. Mersenne or generalized Fermat) each squaring modulo the trial factor will be more than twice as expensive as a squaring modulo c. On the other hand, if c itself has a smallest factor so large as to make finding it practically impossible, then indeed it may prove easier to find a "small" (in the sense that K is small) factor of 2^c - 1 than of c. By its very nature such a factor would not help one in factoring c itself. I'm not sure what point you're trying to make with the K > k^x condition - do you mean to ensure that if k is large (which it must be if c has undergone a sufficient amount of trial factoring), K also will be? Perhaps one should simply exclude such constructions by defining a "genuine composite" as a number which has been shown to be composite by direct (nonfactorial) means, e.g. Lucas-Lehmer, Pe'pin, Proth or any other rigorous compositeness test, and which has no known factors. - -Ernst _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 13 May 2001 20:39:34 -0400 From: George Woltman <[EMAIL PROTECTED]> Subject: Mersenne: Re: Primenet exponents (was: missing exponents?) Hi, At 07:46 PM 5/13/2001 -0400, Nathan Russell wrote: >As it stands, I notice that PrimeNet is given assignments only a few >tens of thousand of exponents in advance. Is this done so that you >have more flexibility, or is it a technical issue with the number of >exponents the server can handle? There is no server limit, nor is there any good reason for my only giving the server a few thousand exponents in advance. Regards, george _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 13 May 2001 21:24:00 -0400 From: George Woltman <[EMAIL PROTECTED]> Subject: Mersenne: Re: 22 below M#38 and counting Hi all, My industrious user (the one testing 4 unassigned exponents below M#38) also notes that there are 6 exponents listed as unassigned and untested in my master database that also appear in the server's cleared exponents report. I've investigated and found the reason, they were tested with the buggy v17 code. So..... the first 6 folks that email me privately can have one exponent each. The race is on, George _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 00:13:52 +0100 From: "Daran" <[EMAIL PROTECTED]> Subject: Re: Mersenne: missing exponents? - -----Original Message----- From: George Woltman <[EMAIL PROTECTED]> To: Achim Passauer <[EMAIL PROTECTED]>; [EMAIL PROTECTED] <[EMAIL PROTECTED]> Date: 12 May 2001 15:41 Subject: Re: Mersenne: missing exponents? >Scott/Entropia gave me a simple tool to do some remote server database >maintenance. I can schedule triple-checks by essentially telling the server >to forget about the double-check result it already has. I assume that means that it forgets that a result has been returned. The /value/ that was returned should not be forgotten. >Hope that helps, >George Daran G. _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 00:14:05 +0100 From: "Daran" <[EMAIL PROTECTED]> Subject: Re: Mersenne: games one can play with genuine composites - -----Original Message----- From: [EMAIL PROTECTED] <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] <[EMAIL PROTECTED]> Date: 12 May 2001 22:57 Subject: Mersenne: games one can play with genuine composites >Please don't think that I'm picking on Brian - Crandall, Papadopoulos >and I made similar claims about F24 being the largest genuine composite >at the time we completed our machine proof of that number, and were >similarly put in our place by one of the reviewers of the resulting >manuscript. OK, so what is the largest /non-trivial/ number for which no factors are known, but a proof of compositeness is? By 'proof', I mean to exclude the possibility that someone randomly generates a couple of large probable primes, multiplies them together, then forgets them. - -Ernst Daran G. _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 00:20:47 +0100 From: "Daran" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: 26 exponents - -----Original Message----- From: Brian J. Beesley <[EMAIL PROTECTED]> To: Nathan Russell <[EMAIL PROTECTED]> Cc: [EMAIL PROTECTED] <[EMAIL PROTECTED]> Date: 12 May 2001 22:01 Subject: Re: Mersenne: Re: 26 exponents >On 12 May 2001, at 15:26, Nathan Russell wrote: > >> On Sat, 12 May 2001 14:20:36 -0400, Jud McCranie wrote: > >> >A thought (but it would mean more work) is that if an exponent expires, it >> >gets reassigned to someone who has completed at least one exponent, to keep >> >the progress going. These unfinished exponents in the 6,000,000 range were >> >originally assigned so long ago that they must have been dropped several times. >> >> I think that's more of a 'quick fix', and might make new participants >> feel that GIMPS doesn't trust them. >> >> It's certainly an interesting topic for discussion, though. > >I don't like the idea, for the reason Nathan indicates - it smacks of >"elitism". As someone currently running a legacy machine, (It's taking 4-5 months to run double-checks in the range under consideration,) I have some thoughts on this. First of all, as Jud notes, the 'elitism' is already there, in that different machines get treated differently in the assignments that they are given. It also lies at the heart of the 'Top producer' chart. Even readers of this list get opportunities to acquire exponents or prebeta-test software, etc., that are not available to the unwashed masses. Secondly, if - when I ask the server to give me "whatever kind of work makes most sense" - it gives me something else, whether out of spurious concern for my feelings or for any other reason, then not only are the programmers betraying my trust in them, they are also indicating that they don't trust me to ask for what I want. If I choose to specify what kind of work I want, I still expect the be given the work that "makes most sense" within that category. I certainly would not expect to be given work that would delay a milestone, given the limitations of my machine. It "makes sense" to offer factorisations to newcomers to the project. It probably would make sense to offer at least one double-check before moving on to first time checks. And it makes sense to offer milestone-blocking work to fast machines with a proven track record of reliability. People will understand this. People do not expect to be given jobs that they are not able to do, or positions of trust within days of joining a new club. Thirdly most people will neither know nor care about the detail of how allocations are made. >A better "fix" would be to patch PrimeNet so that it can assign an >exponent for two LL test runs simultaneously. (Whichever finishes >first becomes the "LL test", the other is the double-check). While that's basically a good idea, it's important to be honest with participants. A patch would not be enough. People need to be informed about departures from documented practice. Regards Brian Beesley Daran G. _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 00:46:52 -0500 From: "Steve" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: 26 exponents >Subject: Re: Mersenne: Re: 26 exponents > >>On 12 May 2001, at 15:26, Nathan Russell wrote: >> >>> On Sat, 12 May 2001 14:20:36 -0400, Jud McCranie wrote: >> <snip> > >Thirdly most people will neither know nor care about the detail of how >allocations are made. That's an excellent point. When I first started I had no idea what exponent I would get or why. > >>A better "fix" would be to patch PrimeNet so that it can assign an >>exponent for two LL test runs simultaneously. (Whichever finishes >>first becomes the "LL test", the other is the double-check). > >While that's basically a good idea, it's important to be honest with >participants. A patch would not be enough. People need to be informed about >departures from documented practice. That _might_ be a good idea, except in the eventual situation where both participants return results indicating their number is indeed prime. Whoever had the slightly slower machine will not be very happy! Steve Harris _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 01:02:16 -0700 From: "xqrpa" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Pentium 4 owners - pre-beta prime95 release available Is ordinary factoring code also present ("Factor Only") and is there a corresponding speed-up? What a prospect: doing a 33M exponent L-L in about 60 days! Thanks And Best Wishes, Stefanovic xqrpasuper - ----- Original Message ----- From: George Woltman <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Saturday, May 12, 2001 6:02 PM Subject: Mersenne: Pentium 4 owners - pre-beta prime95 release available > Hi, > > The P4-optimized version of prime95 is ready for adventurous users > to try out. Ordinarily I would not release a trial version at this point, > but I'm sure > P4 owners are itching for a 3x performance boost. - -mers _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 10:19:53 +0200 From: "Steinar H. Gunderson" <[EMAIL PROTECTED]> Subject: Mersenne: Re: 22 below M#38 and counting On Sun, May 13, 2001 at 09:24:00PM -0400, George Woltman wrote: >So..... the first 6 folks that email me privately can have one exponent each. Yes please -- if there are any left by now :-) /* Steinar */ - -- Homepage: http://members.xoom.com/sneeze/ _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 08:45:59 -0400 From: Nathan Russell <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: 26 exponents On Mon, 14 May 2001 00:20:47 +0100, Daran wrote: >As someone currently running a legacy machine, (It's taking 4-5 months to run >double-checks in the range under consideration,) I have some thoughts on this. > >First of all, as Jud notes, the 'elitism' is already there, in that different >machines get treated differently in the assignments that they are given. It >also lies at the heart of the 'Top producer' chart. Every distributed computing project larger than a few dozen members has such a chart. It would be difficult to keep people interested without one. I know that I don't feel less a part of the project because my placing is above 4,000. >Even readers of this list >get opportunities to acquire exponents or prebeta-test software, etc., that >are not available to the unwashed masses. Very true. Of course, George can hardly contact all several thousand participants when such an opportunity happens. Additionally, GIMPS, unlike most other projects, has exponents taht are 'better' than others. If I run a range of distributed.net keys, it has an equal chance of containing the correct key compared to any other range of equal size. If I run a work unit for seti@home, some work units may be slightly more likely to contain a message, but since a fast computer does multiple work units in one day, it all averages out fairly quickly. >Secondly, if - when I ask the server to give me "whatever kind of work makes >most sense" - it gives me something else, whether out of spurious concern for >my feelings or for any other reason, then not only are the programmers >betraying my trust in them, they are also indicating that they don't trust me >to ask for what I want. The type of work that "makes the most sense" is chosen based on CPU speed, and is based on George's desire to avoid giving machines work that will keep them busy for more than a certain length of time, increasing the risk of an incorrect result. You can override that setting if you have a strong preference. >If I choose to specify what kind of work I want, I >still expect the be given the work that "makes most sense" within that >category. I certainly would not expect to be given work that would delay a >milestone, given the limitations of my machine. This might be a reasonable change in PrimeNet. Personally, I don't think milestones should be a focus of the project, but it is nice when a new one appears on the page. >It "makes sense" to offer factorisations to newcomers to the project. It >probably would make sense to offer at least one double-check before moving on >to first time checks. And it makes sense to offer milestone-blocking work to >fast machines with a proven track record of reliability. People will >understand this. People do not expect to be given jobs that they are not able >to do, or positions of trust within days of joining a new club. I still think that this is very debatable. There should not be a certain /assignment type/ reserved for 'veterans', but it may be reasonable to, e.g., only give triple-checks to accounts that request double-checks, and have returned more than a certain number of results. Note that an exponent given out for triple-checking has a microscopic chance of being prime (something like two in one billion), since it must 1. Be prime (once chance in 60,000-70,000) and 2. Have been missed by both previous tests (1 in 100 for each). >People need to be informed about >departures from documented practice. Are you suggesting that, every time George offers exponents to the members of this mailing list, he should send out a newsletter to every participant - guaranteeing hundreds or thousands of replies for him to deal with? I think there may be no good solution to this. Nathan _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 09:08:19 -0400 From: George Woltman <[EMAIL PROTECTED]> Subject: Re: Mersenne: Pentium 4 owners - pre-beta prime95 release available At 01:02 AM 5/14/2001 -0700, xqrpa wrote: >Is ordinary factoring code also present ("Factor Only") and is >there a corresponding speed-up? The factoring code is present but unchanged. Thus, no speedup. Regards, George _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 10:09:56 -0400 From: Jeff Woods <[EMAIL PROTECTED]> Subject: Re: Mersenne: missing exponents? Chris, I don't think he was bashing Outlook PER SE -- just the version number in question. There have been MANY MANY security fixes to OE since that release, which came with Internet Explorer FOUR a few years back. Even the granola OE that comes with IE 5 (v5.00.2314.1300) has been radically security-patched since release.... At 12:50 PM 5/12/01 +0100, you wrote: > > > > You should use another MailClient as Microsoft Outlook Express > 4.72.3110.1 8) > > Didn't you read all the bad things about Mailwurms etc? > >Sorry, I just felt the urge to say this. There is nothing particualarily >bad about Outlook Express, these various viruses require you to excute >attachments, and you can do that in any mail client.. If any other mail >client gets as popular as OE, then it will start to have viruses aimed at >it's address book too! > >Chris > > > regards, > > > Mohk > > > > > > _________________________________________________________________________ > > Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm > > Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers > > > >_________________________________________________________________________ >Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm >Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 10:27:28 -0400 From: George Woltman <[EMAIL PROTECTED]> Subject: Mersenne: miscellaneous Hi all, The 6 available small exponents are long since gone. One had a P-1 factor found this morning. I've had one other LL result reported, so we're at 20 below M#38 and counting.... Embarrassingly, the P4 version I announced 2 days ago fails the self-test. You would have thought I'd have run that(!), but I ran the QA suite instead. The FFT code is fine, but a change in the way P4 handles carry propagations means you run into trouble if there are too *few* bits per FFT word. Thus, I tweaked the self-test code to not run any small exponents in big FFT lengths. Any LL tests started with the 2 day old version are just fine, the bug was only in the self-test code. Regards, George _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 16:53:21 +0100 From: "Siegmar Szlavik" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: Primenet exponents (was: missing exponents?) On Sun, 13 May 2001 20:39:34 -0400, George Woltman wrote: >At 07:46 PM 5/13/2001 -0400, Nathan Russell wrote: >>As it stands, I notice that PrimeNet is given assignments only a few >>tens of thousand of exponents in advance. Is this done so that you >>have more flexibility, or is it a technical issue with the number of >>exponents the server can handle? > >There is no server limit, nor is there any good reason for my only >giving the server a few thousand exponents in advance. > some months ago I wanted to test 'my lucky number' :-) with Prime95 so I added it manualy to the worktodo.ini file. Everything was OK - until Prime95 contacted the server and got the 'exponent not assigned to you' error message. After that the newly added line disappeared from the worktodo.ini file. Then I tried it with the Advanced->Test option and with that the line remains in the worktodo.ini but now I'm the only one who knows that I'm testing that exponent. OK, I saw on the status page that only 2 exponents were tested in that range (20400000-25330000), but what if one of these is exactly the one? Wouldn't it be usefull to allow the server to accept new exponents if they are 'reasonable'? BTW, what happens when 'AdvancedTests' are completed? Can the server handle the results? greetings Siegmar _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 11:42:34 -0700 From: "Aaron Blosser" <[EMAIL PROTECTED]> Subject: Mersenne: Emails and virus (slightly OT) :) > >Sorry, I just felt the urge to say this. There is nothing particualarily > >bad about Outlook Express, these various viruses require you to excute > >attachments, and you can do that in any mail client.. If any other mail > >client gets as popular as OE, then it will start to have viruses aimed at > >it's address book too! > Chris, I don't think he was bashing Outlook PER SE -- just the version > number in question. There have been MANY MANY security fixes to OE since > that release, which came with Internet Explorer FOUR a few years > back. Even the granola OE that comes with IE 5 (v5.00.2314.1300) has been > radically security-patched since release.... FWIW, one of the best ways to protect your email against virii is at the server level. My current job involves, among other things, administering a couple hundred email domains, and I'm just appalled to see all the viruses that pass through our system each and every day. There are a LOT of viruses out there, and a LOT of people who have no scanning. Of course, we've got our system set to block all VBS files, and we only grudginly allow EXE's (we do scan them though). And of course, in our own company, it was easy enough to just set VBS files to auto-open with notepad rather than running via wscript, merely by changing the default file association. I'll try to keep this a little bit on-topic... Does this mailing list do any sort of virus scanning? I know you can't post to the list unless you're actually on the list, but any scanning going on? Hopefully the folks on this list are bright enough that they know better than to run any executables they receive via email... Aaron _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 12:01:51 -0700 (PDT) From: Gordon Irlam <[EMAIL PROTECTED]> Subject: Re: Mersenne: Emails and virus (slightly OT) :) > I'll try to keep this a little bit on-topic... Does this mailing list do > any sort of virus scanning? I know you can't post to the list unless you're > actually on the list, but any scanning going on? No there isn't any virus scanning going on. There is however a message limit that tends to block most attachments. FWIW, I work at Postini, http://www.postini.com , a company that provides real time email spam and virus blocking services. Customers simply point their MX records at us, and then we take care of the rest, filtering stuff out, and passing on just the good mail. I don't however run base.com mail through Postini. base.com provides me a portal on the net without the Postini filters in place. This is useful for collecting spam which can then be used to tune Postini's spam filtering engine. gordon _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 19:04:39 -0000 From: "Brian J. Beesley" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Re: games one can play with genuine composites On 13 May 2001, at 20:06, [EMAIL PROTECTED] wrote: > True, for composite c, not all factors of 2^c - 1 need have form > 2.K.c + 1; for example, if c = 15, 2^c - 1 = 7.31.151, and the > smallest factor, 7, does not have the form 2.K.15 + 1. However, > if we do not know any of the factors of c, the best we can reasonably > do is to search for factors of the form 2.K.c + 1, which we can do > without knowing any of the factors of c. Yes. > > For c sufficiently large, even sieving for factors of this form > becomes prohibitively expensive - take your own favorite composite > lacking known factors, c = 2^33219281-1. Checking if the smallest > eligible candidate factor 2.K.c + 1 divides C = 2^c - 1 would need > roughly 33219281 squarings modulo the candidate factor, and since > that is not of special form (e.g. Mersenne or generalized Fermat) > each squaring modulo the trial factor will be more than twice as > expensive as a squaring modulo c. Yes, I did point out in my original message on this subject that testing a single factor of M(M(p)) involves about as much effort as running a LL test on M(p). Actually the squaring need not be much more expensive as it is possible to combine squaring and modulo reduction for "Proth" numbers using DWT in much the same way as is done for Mersenne numbers, and 2kM(p)+1 is going to be a Proth number for all reasonable values of k once p is any size at all. > On the other hand, if c itself > has a smallest factor so large as to make finding it practically > impossible, then indeed it may prove easier to find a "small" > (in the sense that K is small) factor of 2^c - 1 than of c. By > its very nature such a factor would not help one in factoring > c itself. Do you mean you can prove that last sentence, or do you just mean we're all so stupid that we haven't found out how to, yet? > > I'm not sure what point you're trying to make with the K > k^x > condition - do you mean to ensure that if k is large (which it > must be if c has undergone a sufficient amount of trial factoring), > K also will be? Yes. If we know that e.g. k>10^40 and we can prove that e.g. K>k^0.1 then we know K>10000. Maybe _much_ bigger. Which implies (even after sieveing out those values of K for which 2KM(p)+1 itself has a small factor, or is congruent to 3 or 5 modulo 8) the work involved in finding that factor is at least thousands of times greater than the work involved in LL testing M(p). In other words, given current hardware, it really is a waste of time, for p ~ 10^6. Conversely, if there is no such limit on x, then we _could_ be lucky and find a factor with a very small K. In fact, given the distribution of factors of Mersenne numbers (even ignoring the special case where p is a 3 mod 4 Sophie Germain prime), it is rather more probable that we _will_ find a factor in a fixed size interval when K is small than it is when K is large. My gut feeling is that there is some limit, i.e. if k is large then K will be large too. However, formal proofs and heuristic arguments both seem to be vanishingly thin on the ground. > > Perhaps one should simply exclude such constructions by defining > a "genuine composite" as a number which has been shown > to be composite by direct (nonfactorial) means, e.g. Lucas-Lehmer, > Pe'pin, Proth or any other rigorous compositeness test, and which > has no known factors. Yes. Otherwise the very question of "what is the largest known composite with no known factors" has no meaning. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 19:04:39 -0000 From: "Brian J. Beesley" <[EMAIL PROTECTED]> Subject: Re: Mersenne: missing exponents? On 13 May 2001, at 19:41, Nathan Russell wrote: > >Another nice thing would be if people who have submitted several results > >that don't match other people's results they could be notified that they > >may have a hardware problem. > > I can't help wondering whether some users would find that to be overly > invasive or startling; however, if I had such a problem - especially > one that could cause slow thermal damage - I would want to know about > it. There is already a mechanism where people can opt in or out of being notified if an assignment is due to expire. Is it reasonable to ask that this may also be used to notify the user if/when it is discovered that they have submitted a result which has turned out to be incorrect? There are two practical difficulties with this approach: (1) the server doesn't know: George discovers discrepancies when he processes PrimeNet transactions into his master database; (2) by the time the discrepancy is found, some considerable time may have elapsed (when are exponents in the 12M range going to get routine double-checks?) and so the reliability or otherwise of the hardware involved in the original test may well be a moot point. > > I deal with altogether too many people on other mailing lists and > newsgroups who believe that it is normal for their machine to take two > attempts to make it through a 25-minute kernel upgrade. Um, upgrading a kernel is essentially nothing worse than a reboot! But yes, there are some people out there with _very_ dodgy hardware. > Granted, a > 5-week GIMPS run is a more stringent criterion, but AFAIK most > machines /should/ be able to survive without more than 1-2 errors a > year (I've had two since I started last January). I agree entirely, though there are causes of errors which are not related to hardware problems per se. Seriously noisy utility power supply and memory corruption due to badly behaved applications running on insecure operating systems probably claim a fair proportion of the victims. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Mon, 14 May 2001 14:51:01 -0500 From: Herb Savage <[EMAIL PROTECTED]> Subject: Re: Mersenne: Emails and virus (slightly OT) :) >Sorry, I just felt the urge to say this. There is nothing particualarily >bad about Outlook Express, these various viruses require you to excute >attachments, and you can do that in any mail client.. Not true! With Outlook Express all you have to do is read the message. The virus can be embedded in the message with Outlook Express. The "Wscript.KakWorm" virus is a particularly bad example of this. For details see: http://www.sarc.com/avcenter/venc/data/wscript.kakworm.html Regards, Herb Savage _________________________________________________________________________ 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 #850 ******************************
