SV: SV: SV: SV: Mersenne: Drifting UP(!) in Top Producers ranking?
Hallo Mary! Ups, I don't suspect you. Maybe the method should be more like: Look at the cleared exponent report to find accounts only or overwhelming returning 66-bits factors. But this might still unwantedly catch you as those factors you find will be in this area. Then one will have to do some TF double checking work of the factors given to the account (can be seen at the assigned tests report). And then again you have to be sure the account also finished it's work on that TF. So as I said it is to complex, to time consuming and not exactly a job for me, as I won't be the GIMPS police. And I very well understand your view TF's starting from eg. 64 bits also have to be done some day. br tsc -Oprindelig meddelelse- Fra: Mary K. Conner Sendt: ti 26-11-2002 00:10 Til: [EMAIL PROTECTED] Cc: Emne: Re: SV: SV: SV: Mersenne: Drifting UP(!) in Top Producers ranking? At 11:04 PM 11/25/02 +0100, =?utf-8?Q?Torben_Schl=C3=BCntz?= wrote: No, and I am not the GIMPS police. It would offcourse be quite easy simply to check all accounts having done 5+ years TF and having more than 0,6 years pr. foundfactor. On the other hand some accounts could be very old and back in those days a factor could have been found in less effort than now a days appr. 0,5 y/ff. NetForce and Challenge seems to be good candidates for accounts with a very low effort pr. ff. Well, you'd nail me. I do expired exponents for the most part, which makes it much less likely that I will find a factor because almost all of those expired exponents have already been done part way, and if there had been a factor in the parts already done, they wouldn't have expired. So I have 8.783 P90 years in factoring, and only 6 factors found. Unless you count the pre-factoring work I turn in manually to George. Lots of factors found there for much less CPU expended. _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
SV: SV: SV: Mersenne: Drifting UP(!) in Top Producers ranking?
-Oprindelig meddelelse- From: Brian J. Beesley Sendt: lø 23-11-2002 13:23 This is not a particularly effective cheat; you still end up having to do significantly more than half of the computational work. Is there any evidence that this may be happening? No, and I am not the GIMPS police. It would offcourse be quite easy simply to check all accounts having done 5+ years TF and having more than 0,6 years pr. foundfactor. On the other hand some accounts could be very old and back in those days a factor could have been found in less effort than now a days appr. 0,5 y/ff. NetForce and Challenge seems to be good candidates for accounts with a very low effort pr. ff. Does it make sense to impose a penalty clause i.e. if someone subsequently finds a factor in a range you claim to have sieved, you lose 10 times the credit you got for the assignment? N.B. There will be _occasional_ instances where an honest user misses a factor, possibly due to a program bug, possibly due to a hardware glitch. I'd rather not like the penalty/ punishment. A reward equal to the full effort of doing the TF would be much better - and under those circumstances no one would try to cheat because a factor found at eg. 63 bits would reward very well. The exponents above 79.300.000 are still candidates, though George has chosen to limit his program to this size and I think with very good reason. Hmm. As it happens, one of my systems has just completed a double-check on exponent 67108763. This took just over a year on an Athlon XP1700 (well, actually it was started on a T'bird 1200). The fastest P4 system available today could have completed the run in ~3 months. The point is that running LL tests on exponents up to ~80 million is easily within the range of current hardware. Yes, but that kind of hardware was not at the market in 1995. But regarding Moores law George should have predicted the P4 and SSE2? Personally I feel it is not sensible to expend much effort on extremely large exponents whilst there is so much work remaining to do on smaller ones. I justify running the DC on 67108763 as part of the QA effort. Sure. Let's get a new prime and let us have it fast. BTW, the list of found factors contains 2.500.000+ but the top producers list only contains 30.000- of these. GIMPS must be responsible for far more than only 30.000 factors. Any explanation for that? Well, there are a lot of factors which can be found by algebraic methods rather than by direct computation: e.g. if p+1 is evenly divisible by 4, and p and 2p+1 are both prime, then 2^p-1 is divisible by 2p+1. Evenly? What about 11, 83, 131 and 251 giving: 3,21,33 and 63. Are these just plain luck or does it exist one p+1 / 4 is not even and the factor 2p+1 does not fit? Have a nice day tsc _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: SV: SV: SV: Mersenne: Drifting UP(!) in Top Producers ranking?
At 11:04 PM 11/25/02 +0100, =?utf-8?Q?Torben_Schl=C3=BCntz?= wrote: No, and I am not the GIMPS police. It would offcourse be quite easy simply to check all accounts having done 5+ years TF and having more than 0,6 years pr. foundfactor. On the other hand some accounts could be very old and back in those days a factor could have been found in less effort than now a days appr. 0,5 y/ff. NetForce and Challenge seems to be good candidates for accounts with a very low effort pr. ff. Well, you'd nail me. I do expired exponents for the most part, which makes it much less likely that I will find a factor because almost all of those expired exponents have already been done part way, and if there had been a factor in the parts already done, they wouldn't have expired. So I have 8.783 P90 years in factoring, and only 6 factors found. Unless you count the pre-factoring work I turn in manually to George. Lots of factors found there for much less CPU expended. _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: SV: SV: Mersenne: Drifting UP(!) in Top Producers ranking?
- Original Message - From: Torben Schlüntz [EMAIL PROTECTED] To: Brian J. Beesley [EMAIL PROTECTED]; [EMAIL PROTECTED] Sent: Monday, November 25, 2002 10:04 PM Subject: SV: SV: SV: Mersenne: Drifting UP(!) in Top Producers ranking? I'd rather not like the penalty/ punishment. A reward equal to the full effort of doing the TF would be much better - and under those circumstances no one would try to cheat because a factor found at eg. 63 bits would reward very well. That would allow another cheat. Current Factoring assignments are prefactored to 2^57, and are intended to be factored to 2^67. If someone were instead just to factor to 2^58, they would have about a 1/58 chance of getting a full credit for less than 1/500th of the effort. If not, then the exponent could be abandoned. This would also have the advantage (from the cheat's POV) of 'poisoning' potential competitors' factoring efforts. IMO people should expect (in the mathematical sense of the word) to get the same amount of credit irrespective of what type of work they do. Also credit should be given for work (honestly) done irrespective of whether the search was successful. The first criterion (only) could be met by crediting only found factors, and giving a higher credit for larger ones, up to the TF limit. I do not think there is any way to allocate credit that meets both criteria, which wouldn't reward cheating in some way. Brian's suggestion is a good one, but I would add that perhaps each user could get an allowance, proportionate to the number of TF assignments returned, that would be deemed to be 'honest' errors, and not penalised. P-1 (which I do almost exclusively) seems to be woefully ill-rewarded. tsc Daran G. _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: SV: SV: Mersenne: Drifting UP(!) in Top Producers ranking?
On Saturday 23 November 2002 02:41, Torben Schlüntz wrote: [... snip ...] Sorry Nathan. It is my fault you read the IMHO paragraph in a wrong way. I meant I had that point of view UNTIL I discussed it.. As George argue: Nobody would do LL if a succesful TF was rewarded the same - he is truly right. From the point of view of the project, the objective is to find Mersenne primes. Finding factors, like completing LL tests returning a non-zero residual, only eliminates candidates. However, from the point of view of league tables, it seems to make sense to award effort expended (in good faith); otherwise there would be only two raks in the table: those who have found a prime, and those who haven't! My goal is to get the succesful TF rewarded a bit higher. As it is now someone might skip the 57-65 range and only do the 66-bit part, thus missing factors and get fully rewarded for only doing half the work. This is not a particularly effective cheat; you still end up having to do significantly more than half of the computational work. Is there any evidence that this may be happening? Does it make sense to impose a penalty clause i.e. if someone subsequently finds a factor in a range you claim to have sieved, you lose 10 times the credit you got for the assignment? N.B. There will be _occasional_ instances where an honest user misses a factor, possibly due to a program bug, possibly due to a hardware glitch. [... snip ...] Composite exponents was removed long before the project. Lucas must have known the exponent needed to be prime. I believe a Mersenne number has to have an exponent which is a positive integer?! The exponents above 79.300.000 are still candidates, though George has chosen to limit his program to this size and I think with very good reason. Hmm. As it happens, one of my systems has just completed a double-check on exponent 67108763. This took just over a year on an Athlon XP1700 (well, actually it was started on a T'bird 1200). The fastest P4 system available today could have completed the run in ~3 months. The point is that running LL tests on exponents up to ~80 million is easily within the range of current hardware. Personally I feel it is not sensible to expend much effort on extremely large exponents whilst there is so much work remaining to do on smaller ones. I justify running the DC on 67108763 as part of the QA effort. BTW, the list of found factors contains 2.500.000+ but the top producers list only contains 30.000- of these. GIMPS must be responsible for far more than only 30.000 factors. Any explanation for that? Well, there are a lot of factors which can be found by algebraic methods rather than by direct computation: e.g. if p+1 is evenly divisible by 4, and p and 2p+1 are both prime, then 2^p-1 is divisible by 2p+1. Also, there are more efficient methods of finding _small_ factors (up to ~2^48) than individually sieving for each exponent. Regards Brian Beesley _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
SV: SV: Mersenne: Drifting UP(!) in Top Producers ranking?
Which remind me, to avoid the cheat possible, the award for finding a factor should be set somehow bigger than only the nearest 6x bits. Give a factor something like the full value of TFing it to 66 bit! IMHO the TF with a factor found should be equal to an LL; but I have already discussed this with George and he is afraid only factoring would be done if the award is that high. That, and you get some rather ridiculous consequences if you do that. Sorry Nathan. It is my fault you read the IMHO paragraph in a wrong way. I meant I had that point of view UNTIL I discussed it.. As George argue: Nobody would do LL if a succesful TF was rewarded the same - he is truly right. My goal is to get the succesful TF rewarded a bit higher. As it is now someone might skip the 57-65 range and only do the 66-bit part, thus missing factors and get fully rewarded for only doing half the work. When George originally created the list of candidate exponents, he eliminated tens of millions of composite exponents, and an infinite number of negative exponents, non-integer exponents, imaginary exponents, and prime exponents above the range of the program. Composite exponents was removed long before the project. Lucas must have known the exponent needed to be prime. I believe a Mersenne number has to have an exponent which is a positive integer?! The exponents above 79.300.000 are still candidates, though George has chosen to limit his program to this size and I think with very good reason. BTW, the list of found factors contains 2.500.000+ but the top producers list only contains 30.000- of these. GIMPS must be responsible for far more than only 30.000 factors. Any explanation for that? br tsc _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
