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Subject: Re: Whither Null Move?

Author: Rémi Coulom

Date: 07:21:12 08/20/01

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On August 20, 2001 at 01:03:30, Georg v. Zimmermann wrote:

>>>
>>>From this +/- oscillation of the score, I guess that you do not give a big
>>>enough bonus for being on the move. This what kills your null move. Just add a
>>>bonus for the player on the move so that the evaluation oscillates as little as
>>>possible. Null move should work much better then.
>>>
>>>Rémi
>>
>>Interesting that you use a bonus.
>>Anyway in this particular position, my guess (just my guess) would be that if
>>r=3 is used, a bonus would be no good for nullmove, as nullmoving steal an
>>important tempo for the side to move.

It is not good for null move because it causes less nullmoves to fail high. But
it is better overall, because it should produce a much more consistant search.

>
>nullscore = -search(-beta, -beta+1, depth-3, 1);
>
>=> he is using R=2
>
>Georg

The value of depth reduction is not relevant here. Whatever the value used for R
(2 or 3), there will be many cases where the reduction will be odd (1 ply away
from the leaves) or even (2 plies away from the leaves).

Remi



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