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Old 2022-04-01, 05:32   #1
Dobri
 
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May 2018

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Default Missed Factors (TF)

This thread is intended to collect information about factors obtained with trial factoring (TF) that have been previously missed due to:
1) Incomplete TF scans for small factors;
2) Faulty TF hardware/software;
3) Fake TF reports;
etc.

An example is
M618033947
for which the 68-bit factor 276413495291788087169 was found.
It was not previously in the GIMPS database and 0.3866 GHz-Days were given for finding it.
Note that zero (0.0000) GHz-Days are given for the TF verification of a known factor.
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Old 2022-04-01, 05:39   #2
Dobri
 
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A second example is

M726064763

for which three (3) factors (34153055801363324180057, 7170112396664438582504527, and 10702385060027676180416983) have been missed for an unknown reason in previous TF tests.
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Old 2022-04-01, 06:10   #3
Uncwilly
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Quote:
Originally Posted by Dobri View Post
A second example is

M726064763

for which three (3) factors (34153055801363324180057, 7170112396664438582504527, and 10702385060027676180416983) have been missed for an unknown reason in previous TF tests.
Those were not missed, expect by your examination of the page you linked to.

34153055801363324180057 was reported on 2016-06-14 by Anonymous and 2022-01-21 by LordJulius

2021-12-28 alpertron F-PM1 Factor: 7170112396664438582504527 / (P-1, B1=1000000, B2=10164924)
2021-12-28 Yzzyx F-PM1 Factor: 7170112396664438582504527 / (P-1, B1=1000000, B2=10164924)

2021-12-26 alpertron F-PM1 Factor: 10702385060027676180416983 / (P-1, B1=1000000, B2=1000000)
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Old 2022-04-01, 06:15   #4
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Quote:
Originally Posted by Dobri View Post
M618033947
for which the 68-bit factor 276413495291788087169 was found.
It was not previously in the GIMPS database and 0.3866 GHz-Days were given for finding it.
Note that zero (0.0000) GHz-Days are given for the TF verification of a known factor.
It not being in the database does not mean it was missed. It was just not found yet. It had a very small factor and those there was no need to continue looking for more factors. We are trying to eliminate exponents that that we will have to run a primality test on. We are not doing exhaustive factoring on all exponents. And even if we were, it would be a long while before we got to that one.
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Old 2022-04-01, 06:22   #5
Dobri
 
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Quote:
Originally Posted by Uncwilly View Post
Those were not missed, expect by your examination of the page you linked to.
Said factors were already known indeed.
The point is that they were missed in subsequent TF tests.
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Old 2022-04-01, 09:05   #6
S485122
 
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Quote:
Originally Posted by Dobri View Post
...
3) Fake TF reports;
An example is
M618033947
...
You mean results like :
Factor: 12965740712769703 / TF: 1-53
Factor: 37915764094923857 / TF: 1-53
Factor: 37915764094923857 / TF: 53-54
Factor: 37915764094923857 / TF: 54-55
The first factor is 53,5 bits the second 55,0 bits. How can a 55 bits factor be found trial factoring from 1 to 53 bits ?
I suppose those where tests ?
As for some no factor results, they may be the result of finishing a bit level even after a factor was found, there used to be an option to do that, but now I can only find such a setting about ECM in undoc.txt.

Last fiddled with by S485122 on 2022-04-01 at 09:28 Reason: stupid formatting by the "smart" software the code tag is not supposed to change the content
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Old 2022-04-01, 09:19   #7
axn
 
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Quote:
Originally Posted by Dobri View Post
The point is that they were missed in subsequent TF tests.
Which "no factor" TF lines missed which factors?
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Old 2022-04-01, 09:26   #8
Dobri
 
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Quote:
Originally Posted by S485122 View Post
You mean results like :
Factor: 12965740712769703 / TF: 1-53
Factor: 37915764094923857 / TF: 1-53
Factor: 37915764094923857 / TF: 53-54
Factor: 37915764094923857 / TF: 54-55
The first factor is 53,5 bits the second 55,0 bits. How can a 55 bits factor be found trial factoring from 1 to 53 bits ?
I suppose those where tests ?
The quoted results above were generated by the mfaktc app. Sometimes, mfaktc gives such output.

What I meant was that the user Anton Repko missed 3 factors in their TF 74-75, 82-83, and 83-84 tests.

Last fiddled with by Dobri on 2022-04-01 at 09:28
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Old 2022-04-01, 10:29   #9
ATH
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Yes, that is a bit strange:

Code:
2022-03-07	Dobri	F	Factor: 10702385060027676180416983 / TF: 83-84
2022-02-23	Dobri	F	Factor: 7170112396664438582504527 / TF: 82-83
.
2022-01-21	LordJulius	F	Factor: 34153055801363324180057 / TF: 74-75
.
2022-01-01	Anton Repko	NF	no factor from 2^82 to 2^83
2022-01-01	Anton Repko	NF	no factor from 2^74 to 2^75
.
2021-12-30	Anton Repko	NF	no factor from 2^83 to 2^84
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