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Subject: Re: Why don't we use stand-pat score in search?

Author: Ricardo Gibert

Date: 16:15:10 05/05/05

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On May 05, 2005 at 10:25:14, Mathieu Pagé wrote:

>On May 05, 2005 at 07:51:33, Ricardo Gibert wrote:
>
>>On May 05, 2005 at 07:31:57, Kevin K wrote:
>>
>>>Do I have to use stand-pat score only in qsearch?
>>>If I use stand-pat score instead of null move in search, what will happen?
>>>I will return if stand-pat score >= beta.
>>
>>Your idea will maximize horizon effect errors. It would mirror the apocryphal
>>strategy of the ostrich which whenever something bad seems to about to happen,
>>it buries its head in the sand to improve its situation.
>>
>>Not a recommended strategy.
>
>I entirely agree with you Kevin, but for Ricardo, I'll explain why stand-pat
>work in qsearch and does not in regular search.

Hmm. I think you have Kevin & Ricardo mixed up.

>
>The idea behind stand-pat evaluation is that at a given node in qsearch if all
>the possible captures are bad for the side to move then the player would play a
>non-capture move. However in qsearch we do _not_ evaluate thoses moves. So we
>know the player would not play one of the captures but we don't know wich other
>move it would play, so we return the current evaluation (That is the best
>approximation of the real value we can do).
>
>During full width search however, all move are examined. So, if they are all bad
>moves we have to return a bad score because there is no other possibly best move
>(That was the case in qsearch)
>
>Mathieu P.



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