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Subject: Re: Nullmove: when to avoid it?

Author: Leen Ammeraal

Date: 09:41:43 02/28/01

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On February 28, 2001 at 06:05:38, Severi Salminen wrote:

>On February 28, 2001 at 05:56:36, Leen Ammeraal wrote:
>
>>I am not sure about when to avoid nullmoves.
>>I omit it:
>>a. when in check
>>b. when there are less than 5 pieces (including pawns) on the board
>>c. when the last move was a nullmove
>>d. at the root node
>>Should I also omit it in some other cases,
>>for example, when any hashmove (even with a low draft) was found,
>>or when beta = alpha + 1?
>
>I avoid it also when it seems that this node is futile: material+MARGIN<=alpha.
>It saved a few nodes and it seems to be quite sound assumption.
>
>Severi

Thanks. Could you please tell me how much is MARGIN? For example,
is it about two pawns?
And I assume that, in the above condtion, 'material' is the result of a
Static Exchange Evaluator, not just the current material balance,
since that would be wrong when we are in the middle of
a swap-off sequence.
Leen




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