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Subject: Re: The Null Move Killer

Author: Stuart Cracraft

Date: 15:23:20 09/30/04

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On September 30, 2004 at 18:07:46, Robert Hyatt wrote:

>On September 30, 2004 at 15:50:43, Stuart Cracraft wrote:
>
>>On September 30, 2004 at 09:38:04, Robert Hyatt wrote:
>>
>>>On September 30, 2004 at 00:52:04, Will Singleton 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
>>>>
>>>>If the previous move was a piece moving near the enemy king, I don't null move.
>>>>Also, don't null near the leafs.
>>>
>>>
>>>That is a bad idea.  That is where most of the _gain_ from null-move happens.  I
>>>do it everywhere without this WAC141 problem stuff bothering anything.
>>
>>Do you mean for both near the leafs and enemy king or only one or the other?
>
>
>Near the leaves...
>
>Actually near the frontier as frontier nodes are those along the outer bound of
>the basic search.  Leaves (in my program) never have null moves anywhere since
>they are in the q-search...

Okay now I'm really confused.

Frontier = depth = 0
Pre-frontier = depth = 1
Pre-Pre-frontier = depth = 2
Leaf = terminal node after quiescence search (no more caps, etc.) possible

Is that how you're classifying it? So no null move at depth = 1 is bad.

Currently my program excludes null move if depth <= 1 (i.e. frontier
or pre-frontier in the above terminology). I have no idea if the above
terminology is generally accepted or not and am curious what others
use.

Stuart



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