mersenneforum.org  

Go Back   mersenneforum.org > Great Internet Mersenne Prime Search > PrimeNet

Reply
 
Thread Tools
Old 2015-06-10, 21:34   #1
guido72
 
guido72's Avatar
 
Aug 2002
Rovereto (Italy)

100111112 Posts
Default This is weird... Isn't it?

Is this the same result or not?...
Attached Thumbnails
Click image for larger version

Name:	weird results.png
Views:	130
Size:	28.2 KB
ID:	12734  
guido72 is offline   Reply With Quote
Old 2015-06-10, 22:56   #2
TheMawn
 
TheMawn's Avatar
 
May 2013
East. Always East.

11×157 Posts
Default

The ECM method isn't deterministic. You don't get a yes-or-no answer from running a single curve. Part of what defines each curve is randomized so no two are likely to be the same. You get increased probabilities of finding a factor (if one is there) by running more. The user probably requested / submitted their curves in batches of 100 which is a bit odd since I think you have seriously diminishing returns at that curve count.
TheMawn is offline   Reply With Quote
Old 2015-06-10, 23:03   #3
guido72
 
guido72's Avatar
 
Aug 2002
Rovereto (Italy)

15910 Posts
Default

Quote:
Originally Posted by TheMawn View Post
The ECM method isn't deterministic.
I know that. My question was about how Primenet may distinguish from two (or more) different results if all the parameters (number of curves, boundaries, ...) it gets are the same... Or it knows that each curve is unic so that each result is unic as well...
guido72 is offline   Reply With Quote
Old 2015-06-11, 00:34   #4
VBCurtis
 
VBCurtis's Avatar
 
"Curtis"
Feb 2005
Riverside, CA

23×72×11 Posts
Default

Quote:
Originally Posted by TheMawn View Post
The ECM method isn't deterministic. You don't get a yes-or-no answer from running a single curve. Part of what defines each curve is randomized so no two are likely to be the same. You get increased probabilities of finding a factor (if one is there) by running more. The user probably requested / submitted their curves in batches of 100 which is a bit odd since I think you have seriously diminishing returns at that curve count.
100 curves is nowhere near diminishing returns for B1 values above 50,000. at B1=110M, something in excess of 10,000 curves are called for before changing B1.

Primenet has no way to know the user isn't submitting fraudulent curve counts. Luckily, the nature of ECM is that a future user running curves of the same or larger size will usually find any factor the fraudulent user "would have" found.
VBCurtis is online now   Reply With Quote
Old 2015-06-11, 03:27   #5
Madpoo
Serpentine Vermin Jar
 
Madpoo's Avatar
 
Jul 2014

1100110010102 Posts
Default

Quote:
Originally Posted by guido72 View Post
I know that. My question was about how Primenet may distinguish from two (or more) different results if all the parameters (number of curves, boundaries, ...) it gets are the same... Or it knows that each curve is unic so that each result is unic as well...
Hard to tell... they were all submitted at the same time but for manual results that's normal.

Since each curve has it's own random starting point, I wonder if a good way to avoid duplicate submissions would be to have Prime95 do a hash of the different ones for each curve and include that in the result. Then the Prime95 checksum would take that into account, which should result in unique results for each set of curves?

I'm probably not saying anything nobody else has ever thought of, so I'll retreat back into my corner now.
Madpoo is offline   Reply With Quote
Old 2015-06-11, 04:40   #6
Dubslow
Basketry That Evening!
 
Dubslow's Avatar
 
"Bunslow the Bold"
Jun 2011
40<A<43 -89<O<-88

160658 Posts
Default

Quote:
Originally Posted by guido72 View Post
I know that. My question was about how Primenet may distinguish from two (or more) different results if all the parameters (number of curves, boundaries, ...) it gets are the same... Or it knows that each curve is unic so that each result is unic as well...
No, PrimeNet unfortunately does not record the sigma for any given curve. (sigma is the standard variable in the literature that uniquely defines each curve.)
Dubslow is offline   Reply With Quote
Old 2015-06-11, 04:50   #7
retina
Undefined
 
retina's Avatar
 
"The unspeakable one"
Jun 2006
My evil lair

3×23×83 Posts
Default

And it is not just ECM that "suffers" from this problem. TF with a negative result is a trust-only thing also. We can't possibly know if any curves/TF were ever run.when the user reports no factors without doing all the work again on another system.

Fortunately the credits earned for no-factor results have no real world meaning so it really doesn't matter too much, the incentive the cheat is very low. More likely it is just a misconfiguration or misunderstanding. Except for perhaps a few extra LL/DC tests that could have been avoided no real harm is caused.
retina is offline   Reply With Quote
Old 2015-06-11, 11:38   #8
ET_
Banned
 
ET_'s Avatar
 
"Luigi"
Aug 2002
Team Italia

2×2,383 Posts
Default

Quote:
Originally Posted by guido72 View Post
Is this the same result or not?...
No, it's not. It was a bunch of 100 curves done on different PCs and submitted all together. The sigma values should be all different.

Unfortuntely, at the moment there is no way for Primenet to tell it from a forged result.

Luigi
ET_ is offline   Reply With Quote
Old 2015-06-11, 12:04   #9
guido72
 
guido72's Avatar
 
Aug 2002
Rovereto (Italy)

3×53 Posts
Default

Quote:
Originally Posted by VBCurtis View Post
Primenet has no way to know the user isn't submitting fraudulent curve counts.
I'm more than sure there's nothing fraudolent! The user is a friend of mine and an absolutely fair and reliable partecipant!!!
I was just wondering... I'm starting right now to look at ECM factoring... Never done that job before...
Regards
guido72 is offline   Reply With Quote
Old 2015-06-11, 12:10   #10
guido72
 
guido72's Avatar
 
Aug 2002
Rovereto (Italy)

9F16 Posts
Default

Quote:
Originally Posted by retina View Post
And it is not just ECM that "suffers" from this problem. TF with a negative result is a trust-only thing also. We can't possibly know if any curves/TF were ever run.when the user reports no factors without doing all the work again on another system.

Fortunately the credits earned for no-factor results have no real world meaning so it really doesn't matter too much, the incentive the cheat is very low. More likely it is just a misconfiguration or misunderstanding. Except for perhaps a few extra LL/DC tests that could have been avoided no real harm is caused.
Do you mean that if one just cuts and pastes in result.txt of MfaktX the usual line "NO FACTOR FOR MXXXXXXX FROM 2^xx TO 2^xx [MFAKTX 0.20 BARRETT76_MUL32_GS] just after havin' changed the exponent there is not any way to know if the test has been actually run?
guido72 is offline   Reply With Quote
Old 2015-06-11, 12:12   #11
guido72
 
guido72's Avatar
 
Aug 2002
Rovereto (Italy)

3·53 Posts
Default

Quote:
Originally Posted by ET_ View Post
Luigi
Ciao Luigi! Tutto OK?
Salutoni!!
guido72 is offline   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Weird Dubslow YAFU 14 2016-01-06 19:34
Weird factors rekcahx Miscellaneous Math 3 2011-11-01 23:25
weird abbreviations science_man_88 Lounge 35 2010-11-28 04:56
something very weird ixfd64 PrimeNet 1 2008-10-16 18:19
Weird LLR FFT timings MooooMoo Riesel Prime Search 2 2007-10-11 08:56

All times are UTC. The time now is 19:31.

Mon Sep 21 19:31:30 UTC 2020 up 11 days, 16:42, 1 user, load averages: 2.54, 2.59, 2.27

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.