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Subject: The Null Move Killer

Author: Stuart Cracraft

Date: 20:52:15 09/29/04


[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



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