Author: Uri Blass
Date: 21:46:26 09/29/04
Go up one level in this thread
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
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.