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Subject: Re: Null-Move: Difference between R = 2 and R = 3 in action

Author: Dann Corbit

Date: 14:05:45 07/15/02

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On July 15, 2002 at 17:02:42, Dann Corbit wrote:

>On July 15, 2002 at 16:43:39, Gian-Carlo Pascutto wrote:
>
>>On July 15, 2002 at 16:19:32, Dann Corbit wrote:
>>
>>>On July 15, 2002 at 16:09:57, Gian-Carlo Pascutto wrote:
>>>[snip]
>>>>Have a foolproof method for identiefying zugzwang?
>>>
>>>Sure.
>>>
>>>Never bother analyzing the root node.  Analyze all forward nodes from the root
>>>instead at ply zero [from current].
>>>
>>>If every evaluation is worse than the current evaluation before analysis, then
>>>you are zugzwang.
>>>
>>>It's also handy for move ordering.
>>
>>This doesn't work :)
>>
>>(Explanation left as exercise to the reader)
>
>It leaves false positives.  It also assumes an exhaustive ply 0 search (eval).

Can you show a case where you are zugzwang and one of the forward moves looks
better for the side to move?

At any rate, it is a simple place to turn on double null move instead of regular
null move.

In the case of a fail low for the current position, it's a good idea to widen
the search anyway.




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