All Things SoB Sieving
The Seventeen or bust project is a
distributed project that aims to prove the Sierpinski
conjecture. In order to achieve this,
prime numbers need to be found for the (what was) 17 remaining numbers of the
form k*2^n+1 for k less than 78557. To
date nine prime numbers have been found, leaving eight to find.
SoB Sieving is a
sub-project that attempts to remove potential candidates by (intelligent) trial
division.
Big positives:
Sieving can be run on any PC, even one that is not able to connect to the Internet.
Sieving is a very efficient method of removing candidates.
Big negatives:
You will never find a prime by sieving, so unless you are
participating in the main SoB project
as well, you will never have the chance to have your name recorded in
history!
The sieving software has not been fully optimised for the P4, as a
result like for like clock speeds, non-P4s will be about 3x faster. P4 owners should consider the P-1
sub-project; take a look at this
excellent site provided by hc_grove
for more information, or the P-1
forum.
To
sieve all you need is a computer, a client, a sob.dat file, and a range.
Regular sieving covers the
candidates that have not been doubled checked by the main part of the project
(currently 1.40M < n < 20M). A
daily updated sob.dat should be
used. It is not important to update
your sob.dat file every day, but if you
do so every (say) month you should notice a small but gradual performance
improvement. A clear text version of the sob.dat file
is available for information. Also a very small zip file that has clear text .dat
files that indicate the next couple of days of main and double check PRP
efforts, and a log file that indicates the daily progress of the shrinkage of
the sob.dat file, again just for
info. For safety (should anything go
wrong with the daily updates) a static 1M < n < 20M sob.dat is available.
The recommended client to
use for regular sieving is Proth Sieve.
Sieve ranges should be
reserved here,
results should be submitted here
when ranges are completed. Please
ensure you are logged in
when submitting factors
For Windows and Linux platforms,
the client of choice is Proth Sieve provided
by Mikael
Klasson, with assistance from Paul Jobling.
Proth Sieve provides
a command line interface, which allows the client to be incorporated in an
automated, batch or service type environment.
Only PCs with very old processors should use the “regular” version. PII, PIII and AMD users should opt for the
cmov version, while P4 users should use the SSE2 version. Mikael also provides a tool call sobistrator that allows
multiple sieve clients to be managed from a single PC.
For those users that demand a
windows GUI, the only option is SobSieve.exe provided by Paul Jobling. SobSieve 1.34
provides an easy to use windows interface, although it should be noted that
this client is about 40% slower the Proth Sieve.
For operating systems other
than Windows and Linux, NbeGone is the client of choice, provided by Phil
Charmody. Check out the various
operating systems supported here. The SoB sieving part of Phil’s site is duplicated here
for those innocent people who live in a country that is in some way supportive
of the 2003/4 US/UK led invasion of Iraq.
If you do want to try accessing Phil’s site try searching for “public
proxies country” in Google.
Sieve ranges should be
reserved here,
results should be submitted here
when ranges are completed. Submit very
large factors here. Please ensure you are logged in when submitting
factors (otherwise scoring is not guaranteed).
As a rough guide, a 100G range will take 3 days on an AMD XP2100+, 6
days on a P3-850 and 15 days on a P2-400.
Again, as a rough guide, if that 100G range is around p=700T, expect it
to yield about 3 factors.
The Seventeen or Bust forum
is the place to find sieving
discussions or more general Seventeen
or Bust discussions.
All
time and 2005 scores are provided for both
sieving and P-1 factoring. These are
updated four times per day at about 03:00, 09:00, 15:00 and 21:00 UK local
time. Scoring is calculated as follows.
A unique factor scores as follows:
p < 40T, score = p/1T
p > 40T, in ‘main active' window, 0 PRP tests
performed, score = (n/1M ^ 2) * 125 * bias
p > 40T, between ‘DC active window’ and ‘n upper
bound’, 0 PRP tests performed, score = (n/1M ^ 2) * 125 * bias (then score will
not increase further).
p > 40T, in 'DC active' window, 0 PRP tests performed, score = (n/1M ^ 2) *
125 * bias
p > 40T, in 'DC active' window, 1 PRP tests performed, score = (n/1M ^ 2) *
125 * 0.6 * bias
p > 40T, in 'DC active' window, 2 PRP tests performed, score = (n/1M ^ 2) *
125 * 0.2 * bias
p > 40T, in ‘completed' window, score = (n/1M ^ 2) * 125 * 0.2
p > 40T, k=prime; as above then frozen when a prime
is found, factors found after the prime score 0
none of the above, score = (as duplicate, see below)
bias = p/40T or current 90% sieve point/40T, whichever
is lower.
A duplicate factor will score as follows:
score = p/100T, capped at 35, or the score (above) as if it were unique,
whichever is lower; when a prime is found all duplicates ever found for that k
score 0.
A unique factor is the first factor found for a candidate.
Scores for each unique factor are remembered. Scores can go up (as an 'active'
window moves to cover a factor that was above the window), but cannot go down
(as a factor moves out of a window).
Scores with 0 PRP tests exiting the main active window
will receive no further increase (i.e. no increase when they reach the DC
active window).
The 'main active' windows is (<next candidate>) < n < (<next
candidate> + 200K).
The ‘DC active' windows is (<next double check
candidate>) < n < (<next double check candidate> + 200K)
A second ‘DC active' windows is (<next double check
candidate2>) < n < (<next double check candidate2> + 10K)
The 'completed' windows is 0 < n < (<next
double check candidate>)
‘n upper bound’ is the lowest of the ‘n bound (upper)’
described here
Excluded factors (those factors not present after sieving
100<n<20M to p=1G) do not score.
Before 21-July-2003 scores were calculated as follows:
n
< 300K, score = p/1T * ((n*n)/(300K * 300K))
300K < n < 20, score = p/1T
n > 20M, score = p/1T *0.05
Duplicates, score = score * 0.01; when a prime is found all duplicates
ever found for that k score 0.
The lowest p for a k/n factor scored as the unique factor,
all higher p scored as duplicates.
Excluded factors (those factors not present after sieving
100<n<20M to p=1G) do not score.
Additional information that
is generated as a result of the scoring is a results.txt format file
with duplicate and excluded factors marked, and user and team allocations fully
identified. This is updated daily at
about 03:00.
Here we attempt to determine
those ranges have been fully sieved, and those that require further work.
|
All these are updated four
times per day at about 03:00, 09:00, 15:00 and 21:00 UK local time.
Date |
Event |
User scores |
Team scores |
Project statistics |
19 Oct 2005 |
Status soon after k= 4847
removed (first day of sieving 8 k). |
|||
19 Oct 2005 |
Status prior to prime
found for k= 4847 (last day of
sieving 9 k). |
|||
17 Jun 2005 |
Status soon after k= 27653
removed (first day of sieving 9 k). |
|||
16 Jun 2005 |
Status prior to prime
found for k= 27653 (last day of
sieving 10 k). |
|||
04 Jan 2005 |
Status soon after k= 28433
removed (first day of sieving 10 k). |
|||
03 Jan 2005 |
Status prior to prime
found for k= 28433 (last day of sieving 11 k). |
|||
03 Sep 2004 |
300T completed |
|||
20 Dec 2003 |
Status soon after k=5359
removed (first day of sieving 11 k). |
|||
16 Dec 2003 |
Status prior to prime
found for k=5359 (last day of sieving 12 k). |
|||
12 May 2003 |
Another early sieve
statistic (17T completed). |
|||
01 Apr 2003 |
Earliest sieve statistics
I can find (10T completed). |
P-1 sub-project information provided by hc_grove.
A daily updated P-1 sob.dat – ONLY FOR P-1 factoring. Use and regularly update with this file
(only 16KB) and you don’t need to worry about downloading results.txt
(1.9MB).
Background
information on sieving ...and a bit more
Largest known factors
found using Pollard’s P-1 method (good indication of the B1 and B2
parameters that need to be used to break records, nothing from SoB yet!)
Largest 200 known
primes (look for SBn in the who column for SoB contributions)
Any problems? Contact me through the SoB
forum here
Page last updated by Mike Henley, Saturday, 07 October 2006.