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  1. #1
    Got it earlier today, thanks.

  2. #2
    Are you still looking for log files? I've got a few from just over a year ago, don't know how helpful they would be. Let me know if you could use them, and I'll do some digging to get them you.

  3. #3
    Quote Originally Posted by endless mike View Post
    Are you still looking for log files? I've got a few from just over a year ago, don't know how helpful they would be. Let me know if you could use them, and I'll do some digging to get them you.
    Yes, and yes. ALL log files will be useful. If everything was indeed lost, all tests for which there are no records will need to be redone. So every result from a log file is one less result that will eventually have to be repeated.

  4. #4
    Quote Originally Posted by AG5BPilot View Post
    Yes, and yes. ALL log files will be useful. If everything was indeed lost, all tests for which there are no records will need to be redone. So every result from a log file is one less result that will eventually have to be repeated.
    First, I have several log files that I will send after the last one finishes.

    Secondly, why is it necessary to redo all of the old ones? We know that all exponents below a certain limit (27,700,000) have been checked - I don't see a need to redo those.

  5. #5
    Quote Originally Posted by jMcCranie View Post
    First, I have several log files that I will send after the last one finishes.

    Secondly, why is it necessary to redo all of the old ones? We know that all exponents below a certain limit (27,700,000) have been checked - I don't see a need to redo those.
    We don't know which ones were double checked -- and at PrimeGrid I've got a really good window into the quality -- or lack thereof -- of the computers used in distributed computing. In general, we no longer trust any results unless they're double checked. The problem with not immediately double checking results is that when a computer starts going bad, you have no way of detecting it. So any results that don't have matching residues from different computers are suspect. Unless we get really lucky, except for whatever we can get from log files, we have no residues at all on 4 of the 6 k's.

    Calculation errors are proportionally more likely to occur on larger candidates, especially when the error rate is fairly low, but non-zero.

    Our position on double checking is especially rigid when it comes to conjectures like SoB. Consider a hypothetical k where the first prime is at n=100,000, and the second prime is at n=100,000,000. If you miss the first prime because of an undetected computation error, many years of unnecessary computing will be wasted searching for the second prime.

    It's actually not as horrible as it might seem at first glance. The vast majority of candidates are small and can be rechecked much faster than the original search.

  6. #6
    Quote Originally Posted by AG5BPilot View Post
    We don't know which ones were double checked
    Unlike the Mersenne prime search, we only need to double check positive results. The time double-checking is better spent checking new numbers. For Mersenne primes, we want a complete list. For 17-or-bust, we only need to find a prime for each coefficient. If we get a false negative, no harm is done if we find a prime for that coefficient.

  7. #7
    Quote Originally Posted by jMcCranie View Post
    Unlike the Mersenne prime search, we only need to double check positive results. The time double-checking is better spent checking new numbers. For Mersenne primes, we want a complete list. For 17-or-bust, we only need to find a prime for each coefficient. If we get a false negative, no harm is done if we find a prime for that coefficient.
    A false negative would mean a missed prime. Potentially wasted years of computing would count as harm in my book. That's the main reason I gave up on SOB and went back to GIMPS.

    Quote Originally Posted by AG5BPilot View Post
    Consider a hypothetical k where the first prime is at n=100,000, and the second prime is at n=100,000,000. If you miss the first prime because of an undetected computation error, many years of unnecessary computing will be wasted searching for the second prime.

  8. #8
    Quote Originally Posted by AG5BPilot View Post
    Yes, and yes. ALL log files will be useful. If everything was indeed lost, all tests for which there are no records will need to be redone. So every result from a log file is one less result that will eventually have to be repeated.
    I will get my results files to you; might take me until Monday though. Real life responsibilities come first.

  9. #9
    Quote Originally Posted by endless mike View Post
    I will get my results files to you; might take me until Monday though. Real life responsibilities come first.
    Thank you! There's no need to feel rushed. Louie can, of course, take as much time as he needs, and we're not going to rush him. We're not going to take any action until he determines if restarting SoB is possible.

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