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Subject: Re: When to do a null move search - an experiment

Author: Gerd Isenberg

Date: 08:47:03 04/28/04

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On April 28, 2004 at 07:41:36, Omid David Tabibi wrote:

>On April 27, 2004 at 15:06:29, Gerd Isenberg wrote:
>>On April 27, 2004 at 03:33:26, Bas Hamstra wrote:
>>>About double nullmove: I tested this in some pawnendgames to see if it could
>>>handle zuzwang problems, but I don't see it perform any better than normal
>>>nullmove. Can Vincent or you post a position where double null outperforms
>>>normal null? I agree the idea is elegant, but I just don't see it work.
>>Hi Bas,
>>i don't use double nullmove, but a verification search with same R, if nullmove
>>fails high. Some of my favorite zugzwang positions:
>>CTT4-11 Crafty-IsiChess:
>>[D] 8/8/1p1r1k2/p1pPN1p1/P3KnP1/1P6/8/3R4 b - - ; bm Nxd5
>>[D] 4KBkr/7p/6PP/4P3/8/3P1p2/8/8 w - - ; bm g7
>Falcon using verified null-move pruning solves both positions in 1 second.

Wow, that's great.
IIRC IsiChess needs some more time for the first one (~5 seconds).
What about combining a reduced search, for Nullmove observation with detection
of singularity and a kind of IID or even ETC? I guess there is still huge room
to look for more improvements with Nullmove related stuff.



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