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Subject: Re: During Null Move search

Author: Robert Hyatt

Date: 08:38:42 06/03/98

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On June 03, 1998 at 09:52:34, Roland Pfister wrote:

>On June 03, 1998 at 08:31:28, Robert Hyatt wrote:
>>On June 03, 1998 at 02:45:34, Roland Pfister wrote:
>>>So do I. I just don't allow extensions if a nillmove is in the path.
>>I do normal extensions and everything else, as I want that null move
>>search to fail high... and the best way to do so is to follow checks and
>>so forth to prove that "passing" is really ok, showing that the current
>>position is good enough that even passing doesn't hurt.
>Sounds plausible. My idea is that I search nullmoves with reduced
>depth and I don't want to undo that by following extensions. My tree
>is smaller and I hope to get to the next iteration by doing that, so
>that it will
>compensate for reducing my depth because I did not follow the
>Some time ago I did a statistic of cutoffs ( its actually in the
>version of Patzer ) and noticed that nullmoves get the highest success
>rate ( 70 to 90 % iirc ), so I never thought of changing my way to do
>When I find the time I will try both ways on BS2830 or LCT2.
>I think that I have read something like that ( we reduced the depth,
>so we won't increase it by doing a extension ) in the Crafty source.
>Could be a year ago or so.

I'll look at the comments, but the search definitely doesn't know that
there is a null-move in the history, except that it does know that the
move at the previous ply was a null or not to avoid back-to-back nulls.

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