Author: Joachim Rang
Date: 08:13:28 09/30/04
Go up one level in this thread
On September 30, 2004 at 02:53:16, Stuart Cracraft wrote: >The null move killed, win-at-chess 141, has itself >finally been killed, vanquished with the help of >two board contributors whose combined suggestion >led to a 17-fold reduction in time-to-solve. > >This posting announces those winners. First the >stats! > >Now solved in 5.49 seconds on a P3 @ 1ghz it would be >solved in under 2 seconds on more modern equipment. >Formerly it took 95 seconds to solve. > >That's good enough for me. And it's good enough to win >the $50 contest posed recently since it broke the >10-second-and-under-barrieras posed in the contest >posting. > >The search: > >Alpha=-1332 Beta=-531 Maxdepth=9999999 MaxTime=99999 > 1/ 9 g2f1 0.00 -953 511 g2f1 f4d5 > g2f1 f4d5 > 2/ 9 g2f1 0.01 -953 884 > g2f1 f4d5 c1g5 > 3/12 g2f1 0.06 -953 11929 > g2f1 f4d5 c1g5 d5f6 > 4/16 g2f1 0.39 -953 72781 > g2f1 f4d5 b3d5 c6d5 f1g2 d6e7 > 5/24> g2f1 3.83 -552 978925 > g2f1 b5b4 b3a4 f4d5 f6g5 d5e7 > 5/25 c1f4 5.49 2260 1420038 c1f4 d6f4 h4h5 g6h5 h1h5 f4h6 h5h6 c7g3 g2g3 d7d >6 > c1f4 d6f4 h4h5 g6h5 h1h5 f4h6 h5h6 c7g3 g2g3 d7d >6 > 6/25 c1f4 6.06 2260 1519145 > c1f4 d6f4 h4h5 g6h5 h1h5 f4h6 h5h6 c7g3 g2g3 d7d >6 > >And with it the announcement -- because of the contribution >of Will Singleton in indicating that null move should be >avoided before leaves in the main search (and the sense >of a comparison in an old commented out section of the >code associated with disabled null move verification having been >intended to do what Will suggested but having been miscoded >by me and then #ifdefed out months ago) and Uri Blass' >comments about my recaptures being too free and easy, >the program went from a total of 95 seconds >for wac 141 to 5.49 after these two suggestions were >implemented. > >So Will and Uri are the winners, if they wish to accept, >of the divided $50 prize. Because Will's contribution was >more significant but less work for him and Uri's contribution >was less significant but with more work for him, but in either >case without the change from the other's suggestion the result >would not have been as dramatic getting down to <= 10 seconds >as stated in the earlier contest challenge a day or two ago, >the award has been divided in half for the 2 winners. > >Will and Uri are welcome to send me, and only if they wish >to collect, their postal mail addresses, to cracraft@cox.net >and a check for $25 will be sent out to each. > >In the future, more contests will be held like this whenever >I run into a huge roadblock but I see none looming presently, >including a rather unusual one that I am not ready to announce. > >Thanks everybody for the help on 141 -- and thanks to Will >Singleton and Uri Blass. > >Stuart Fruit finds it with Nullmove=R3 and disabled Verification Search on depth 8 after 3 (8 seconds for mate score on depth 9) seconds on Athlon XP 1500 MHz. I don't think Nullmove is the problem here. If I disable Nullmove the picture doesn't change much (same depth slightly longer search). But if I disable Check Extensions and Checks in QS, it takes depth 12 and 57 seconds on Athlon XP 1500 MHz. On the other hand without check extensions and disabled Nullmove it takes Fruit depth 11 and 37 seconds to find the mate. So my conclusion would be, if you have check extensions disabling nullmove does not help, if you have no Check Extensions it may help. regards Joachim
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