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Subject: Re: An MTD(f) question about NULL MOVE searching

Author: Vasik Rajlich

Date: 11:52:35 07/16/04

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On July 16, 2004 at 13:49:41, Tord Romstad wrote:

>On July 16, 2004 at 13:40:52, Vasik Rajlich wrote:
>>On July 16, 2004 at 12:13:25, Fabien Letouzey wrote:
>>>As for the "true bounds", Tord mentionned that he used some form of "aspiration"
>>>together with MTD(f).  The guess part of aspiration can obviously be applied to
>>>any algorithm and he makes some decisions during the search depending on those
>>>values.  So I am not sure about the "decisive advantage" although I don't like
>>>the idea of MTD(f) at all.
>>Maybe Tord found something interesting. In MTD (f) you do have root aspiration
>>values, but these don't seem that useful.
>The idea is not mine; I learnt it from Andrew.  At the beginning of each
>iteration, I assume that the score will end up within a window of +- 2 pawns
>centered around the result of the previous iteration.  I use this window
>as a basis for pruning decisions.  When it turns out that the score is
>likely to end up outside the window, I clear the hash table and restart
>the iteration with most speculative pruning tricks disabled.

Aha, thanks. Although that seems very wide ...


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