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Subject: Re: Double Nullmove

Author: J. Wesley Cleveland

Date: 14:14:26 04/25/02

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On April 25, 2002 at 13:26:19, Andreas Herrmann wrote:

>On April 25, 2002 at 11:58:53, Russell Reagan wrote:
>
>>What is double null move? I assume it's playing two null moves one after
>>another, but how is it used to detect zugzwang?
>>
>>Russell
>
>The first null move is for detecting a zugzwang. This first nullmove you have to
>make with a reducing + 1. Excample: if your normal null move uses R=3 then use
>for the first detecting null move  R=4.
>Only if the first null move responds a value >= beta then you do the second null
>move.
>

I have not implemented this yet, so this is speculation. Do a normal nullmove.
If it fails low by a significant margin (.5 pawn ?), and you are not too near
the leaf, do a search without reversing colors, reducing the depth by R+2 (or
R+1). If this fails low (for the other side), you may have a zugzwang so do a
full search.



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