
View Poll Results: A new subforum dedicated to Fermat factorization?  
Yes, great!  8  34.78%  
Hm... why not?  4  17.39%  
Dunno.  5  21.74%  
Useless...  6  26.09%  
Voters: 23. You may not vote on this poll 

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20100328, 22:43  #1 
Banned
"Luigi"
Aug 2002
Team Italia
4766_{10} Posts 
Fermat factorization subforum poll
I think a new subforum dedicated to Fermat factorization would be great. Just think about:
 ECM management  Algorithms discussion  Software development  Heuristics  Correlation among different factorization systems  History  Hints on use of different software Last fiddled with by ET_ on 20100328 at 22:50 Reason: Added some reasons to vote... 
20100328, 23:15  #2 
Mar 2006
Germany
2·1,423 Posts 
... Links to pages of current/summary status

20100328, 23:47  #3 
Mar 2003
New Zealand
13×89 Posts 
... GFN factorisation too?

20100328, 23:53  #4 
P90 years forever!
Aug 2002
Yeehaw, FL
67·107 Posts 
Recent successes notwithstanding, I suspect such a subforum would be pretty quiet. Almost all the issues above relating to further research and optimum program usage apply to factoring other numbers.
How about a sticky in the factoring format that can provide links to related web pages and pointers to the occasional ECM success threads? 
20100329, 04:47  #5 
"Phil"
Sep 2002
Tracktown, U.S.A.
1,117 Posts 
I agree with George that a sticky thread would be more useful than a subforum. One thing that is missing that was available on the old pages is a summary of P1 limits on Fermat numbers. As Ernst has pointed out, P1 might have discovered the most recent factor of F22 had it been pushed far enough.

20100329, 08:16  #6  
Banned
"Luigi"
Aug 2002
Team Italia
4766_{10} Posts 
Quote:
I remember a bunch of messages written by Ernst, Phil and Mike and related to this subject that I would like to see in the Fermat sticky thread: ECM curves comparison between Prime95 and GMPECM, tables about memory allocation and a few ideas about sieving large ranges. I also would like to start talking about porting GMPECM under CUDA after Oliver (a.k.a. TheJudger) completes his GPUaware Mersenne factorization applet. And I feel the need to port FermFact program under 64 bit (or Linux at least), or ask Geoff instructions on how to implement a similar sieve. I exchanged messages with Wilfrid Keller, and he felt a bit puzzled noting that there is little coordination on the ECM side of Fermat factorization. Now, with the new version of PrimeNet, things are getting better, but there are still users that don't (or don't care to) report their (often manual) curves to GIMPS. I don't explicitly ask for a subforum: a sticky thread may suffice, but there is really much to talk about IMHO. Luigi Last fiddled with by ET_ on 20100329 at 08:18 

20100329, 15:47  #7 
Oct 2006
Berlin, Germany
2^{2}·3·7^{2} Posts 
Hi,
I'm not really a math freak and don't know much about all the different numbers to factorize and the alg. behind. To make it much easier to contribute to Fermat factorization I would like to see a page with all remaining composites (not only C223232, but the real value) and how many ecm curves were already done for different B1 and how many are left. yoyo 
20100329, 16:12  #8  
"Tapio Rajala"
Feb 2010
Finland
3^{2}×5×7 Posts 
Quote:
The leading edge of ECM factoring that is reported to PrimeNet is, in my opinion, well presented at www.mersenne.org/report_ECM/. As Luigi said: the problem is that not all effort is reported to PrimeNetserver. The page is showing only the status of the current bounds that are assigned by the server, but that should be enough for most purposes. The trial factoring ranges for larger Fermat numbers are in my opinion also adequately presented at www.fermatsearch.org. On the original question about the need for a subforum: I don't think there is (yet) a need for it. I mean, we are probably not getting 2 factors a month from this point on (or are we? ) A sticky with the recent history and links to all the relevant forumthreads (and to sites like the ones mentioned in this post) would be perfect. Last fiddled with by rajula on 20100329 at 16:13 

20100329, 17:32  #9  
Bamboozled!
"πΊππ·π·π"
May 2003
Down not across
5×2,053 Posts 
Quote:
Paul 

20100506, 15:53  #10 
Banned
"Luigi"
Aug 2002
Team Italia
2·2,383 Posts 
The poll is clsoed... Luigi 
20100709, 13:45  #11  
Aug 2004
7 Posts 
Quote:
One that has especially interested me for lack of interest is the cofactor of F_{25}. F_{25} already has three prime factors known, but the most recently found was discovered as long ago as 1987. What surprises me is that no effort seems to have been made to prove the cofactor of F_{25} as composite, though F_{24} was proven composite as early as 1999. I know from having read about Fermat numbers for years that it is extraordinarily improbable that the cofactor of F_{25} would be found to be a probable prime, and totally impossible given that F_{25} has over ten million digits (I am not sure how many exactly) that it could be proven if it were a probable prime. Another thing that could be discussed on a Fermat subforum is factors of generalised Fermat numbers. I know of tables of these for bases 6, 10 and 12 with full factorisations as known to date. The most wanted number here is F_{9}(10) or 10^{512}+1. F_{9}(10), though smaller than the ordinary Fermat number F_{11}, has not been completely factored twentytwo years after F_{11} was factored in 1988. It is known that F_{9}(10) has at least five prime factors, and that: Code:
Last fiddled with by xilman on 20100709 at 15:26 Reason: Add [ code] tags for ease of reading. 

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