Author: martin fierz
Date: 03:35:11 09/30/04
Go up one level in this thread
On September 30, 2004 at 05:00:31, Uri Blass wrote: >On September 30, 2004 at 04:52:12, martin fierz wrote: > >>On September 30, 2004 at 00:46:26, Uri Blass wrote: >> >>>On September 29, 2004 at 23:52:15, Stuart Cracraft wrote: >>> >>>>[D] 4r1k1/p1qr1p2/2pb1Bp1/1p5p/3P1n1R/1B3P2/PP3PK1/2Q4R w - - bm Qxf4; >>>> >>>>In this position I had everything turned on and got the solution >>>>in a little more than 1 1/2 minutes: >>>> >>>> 1/11 g2f1 0.01 -953 945 g2f1 f4d5 >>>> g2f1 f4d5 >>>> 2/12 g2f1 0.01 -953 1644 >>>> g2f1 f4d5 c1g5 >>>> 3/12 g2f1 0.02 -953 5064 >>>> g2f1 f4d5 c1g5 d5f6 >>>> 4/20 g2f1 0.09 -953 20655 >>>> g2f1 f4d5 b3d5 c6d5 c1c7 d6c7 f1g1 >>>> 5/22 g2f1 0.65 -953 168943 >>>> g2f1 b5b4 b3a4 f4d5 f6g5 d5e7 >>>> 6/26 g2f1 2.59 -953 620310 >>>> g2f1 b5b4 mtmt >>>> 7/32> g2f1 60.58 -552 14192153 g2f1 e8c8 c1b1 f4d5 b1e4 d6b4 f6e5 c7b6 >>>> g2f1 e8c8 c1b1 f4d5 b1e4 d6b4 >>>> 7/34 c1f4 99.42 5113 24537823 c1f4 e8e6 f4g5 d7e7 b3e6 e7e6 h1d1 d6e7 f6e7 >>>> c1f4 e8e6 f4g5 d7e7 b3e6 e7e6 h1d1 >>>> >>>> >>>>I turned off null move (R=2) and got the solution in about 11 seconds: >>>> >>>>Alpha=-1332 Beta=-531 Maxdepth=9999999 MaxTime=99999999 >>>> 1/11 g2f1 0.01 -953 908 g2f1 f4d5 >>>> g2f1 f4d5 >>>> 2/12 g2f1 0.01 -953 1565 >>>> g2f1 f4d5 c1g5 >>>> 3/14 g2f1 0.07 -953 20084 >>>> g2f1 f4d5 c1g5 d5f6 >>>> 4/22 g2f1 0.60 -953 131543 >>>> g2f1 f4d5 b3d5 c6d5 c1c7 d6c7 f1g1 >>>> 5/26>g2f1 6.80 -552 1607444 >>>> g2f1 b5b4 b3a4 f4d5 f6g5 d5e7 >>>> 5/36 c1f4 10.70 2260 2466497 c1f4 d6f4 h4h5 g6h5 h1h5 f4h6 h5h6 c7g3 g2g3 d7d6 >>>> >>>> c1f4 d6f4 h4h5 g6h5 h1h5 f4h6 h5h6 c7g3 g2g3 d7d >>>> >>>>So now my question is, would it make sense to consider an idea of >>>>disabling null move under additional circumstances if those >>>>circumstances can be identified. >>>> >>>> endgame >>>> side to move in check >>>> inside principal variation >>>> last move a null move >>>> >>>>These are the ones I disable for -- I don't disable null move for >>>>any material-related or alpha/beta related measures but perhaps >>>>I should. Are any in common use? >>>> >>>>Stuart >>> >>>It is better to disable your recapture extensions. >>>The problem here is not null move pruning and null move pruning willnot change >>>the depth that you solve the problem when you will implement correctly checks in >>>the qsearch. >>> >>>The target of chess programs is not to solve 141 faster but to play better. >>>I am almost sure that if only the recapture extension save you many plies in 141 >>>then you implement it in a way that is counter productive for games. >>> >>> >>>I wonder how do you get depth 5 without null move pruning >>> >>>Can you post the remaining depth after every move in the line >>>1.Qxf4 Bxf4 2.Rxh5 gxh5 3.Rxh5 Bh6 4.Rxh6 Rd6 Rh8# >>> >>>There are no checks in this line except the mate and you do checks in the >>>qsearch so without recapture extensions you need at least 9 plies for it(after 8 >>>plies you enter qsearch after Rd6 and do not find the move Rh8 mate. >>> >>>If recapture extensions lead to 4 plies extension then it seems clear that your >>>new program will be clearly weaker in games. >>> >>>I suspect that you extend 4 plies in this line because you extend 1 ply every >>>time that the last 2 moves are captures. >>> >>>It is clearly a bad idea to do it and it is clear that even with more reasonable >>>restriction of the recapture extension it is not productive for a lot of >>>programs. >>> >>>I suggest that you test the version with the recapture extension in games >>>against the version without the recapture extension if you do not believe me >>>that your recapture extension is a bad idea. >>> >>> >>>Uri >> >>hi uri, >> >>where do you see recapture extensions influencing WAC.141? the main line has no >>single "recapture" if you define it as "capture of a piece of the same value, on >>the same square, on two successive plies". i think that is the normal definition >>of recapture. >> >>what am i missing? >> >>cheers >> martin > >It seems that >Stuart Cracraft defines it as 2 consecutive captures. > >He probably extend the line that I showed by 4 plies for that reason: > >1.Qxf4 Bxf4 =>extension >1...Bxf4 2.Rxh5=>extension >2.Rxh5 gxh5=>extension >2...gxh5 3.Rxh5=>extension > >I tried to understand how can he get Wac141 at depth 5 without null move pruning >when he is using no checks in the qsearch and no mate threat extensions and this >was my conclusion and based on his response I understand that my conclusion was >correct. > >Uri hi uri, i see. now i also understand your recommendation to limit recaptures - i think it's rather obvious that this type of recapture extension is horrible! for me, using a normal recapture extension (as defined in my previous post) is doing ok - i don't really see a difference compared to not doing it in engine matches, it scored a tiny bit better but nothing significant. i left it in since it seems sensible to me "on general grounds" i.e. as a human player i also use this extension :-) cheers martin
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