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Old 2008-09-16, 16:43   #1
ewmayer
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Default You would-be sleuths made it much harder...

...than it needed to be in the case of the larger of the 2 newly-discovered primes.

If you had googled for

Code:
www.mersenne.org/primenet/cleared.txt 0000000000000000
any time from roughly a day after the first [larger] prime was listed as "prime unverified" on the Primenet server up until late last week, here’s the "result 1 of 1" you would have seen [this is a snip form a screenshot from the actual Google result as it appeared in my Firefox session]:

p43112609.bmp

George explains:
Quote:
For three hours after the second Mersenne was reported, M43112609's zero residue was displayed. Scott's reporting code could only mask one prime and generate one bogus residue. That's why I deleted 43112609 from the database for several days.

Yesterday, I put 43112609 back in the database with a composite status, and flagged one of the other exponents that hour as prime.

Amazingly, no one noticed during that 3 hour interval.
Google did.

Last fiddled with by ewmayer on 2008-09-16 at 16:44
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Old 2008-09-16, 16:49   #2
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Well sure, when you know exactly what to look for it all seems very easy.

Luckily for you guys the Google search engine wasn't interested enough to post here.
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Old 2008-09-16, 16:53   #3
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Quote:
Originally Posted by retina View Post
Well sure, when you know exactly what to look for it all seems very easy.
Anyone familiar with GIMPS knows what Res64 a new prime will have, and where it will appear. What's so "exact" about that, in the sense you seem to imply, i.e. that it requires insider knowledge?
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Old 2008-09-16, 17:00   #4
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Quote:
Originally Posted by ewmayer View Post
Anyone familiar with GIMPS knows what Res64 a new prime will have, and where it will appear. What's so "exact" about that, in the sense you seem to imply, i.e. that it requires insider knowledge?
No, I mean that since you knew that the report file has an all zero residue then if you search for it is easy to find. But I expect, that like me, other people here would not expect that the report file would ever have a zero residue posted and thus we would not have bothered to search for it.
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Old 2008-09-17, 04:10   #5
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Quote:
Originally Posted by ewmayer View Post
If you had googled for

Code:
www.mersenne.org/primenet/cleared.txt 0000000000000000
any time from roughly a day after the first [larger] prime was listed as "prime unverified" on the Primenet server up until late last week, here’s
Didn't you mean "... any time during a three-hour interval after the second [smaller] prime was listed as "prime unverified" on the Primenet server, here’s ...", in accordance with George's explanation?

Quote:
Originally Posted by ewmayer View Post
What's so "exact" about that, in the sense you seem to imply, i.e. that it requires insider knowledge?
A three-hour interval, rather than the multi-week span.

Last fiddled with by cheesehead on 2008-09-17 at 04:18
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Old 2008-09-17, 09:49   #6
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I found your exposure of using a 4096K FFT enough of a giveaway
to predict ~42M and ~38M for the size of the primes.
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Old 2008-09-17, 18:09   #7
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Quote:
Originally Posted by davieddy View Post
I found your exposure of using a 4096K FFT enough of a giveaway
to predict ~42M and ~38M for the size of the primes.
Well, for all anyone knew, we could have had thread-related problems at 2048K as well, forcing us to 4096K even for numbers < ~39M ... but yeah, once the ETC for the verify of the second-number verify was given, it was pretty obvious that the 2 primes would fall on either side of the 2048K FFT-length's exponent cutoff.
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