Author: Stuart Cracraft
Date: 11:23:45 09/30/04
Go up one level in this thread
On September 30, 2004 at 11:13:28, Joachim Rang wrote: >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 I have quasi-infinite check extensions (99) in main search and quiescence. Not sure your diagnosis in my regard as confining my null move additionally by depth >= 1 as well as limiting my unlimited recapture defined as two back-to-back captures by anything of anything on the same square to only ply<=iply+1 where iply is the iterative deepning ply, those two things fixed it with quasi-infinite check extensions. My maximum ply depth for any search is 99 ply.
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