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Subject: Re: futility pruning?

Author: Matthias Gemuh

Date: 01:55:40 11/09/03

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On November 09, 2003 at 03:53:24, Daniel Shawul wrote:

>
>
>>I do not remember if Ernst's paper said that you make the move first and then
>>decide if it is futile.
>>
>>If it did, then it's definitely killing all the interest of futility pruning at
>>depth 1!
>>
>>The idea is to prune before you make the move. So you stay at depth==1, look at
>>the move, and say "hey, this move looks completely futile, let's ignore it!".
>>
>>
>>
>>    Christophe
>
>A futile move is futile before you make or after you make it.
>    before
>          mat_bal + move_gain + margin < alpha => futile move
>    after
>          mat_bal + margin < alpha => futile move
>Anyway my question is since you go directly to quiescent search
>(where stand pat cutoff of all futile moves occur) after making the move,
>we only saved ourselves "making of the futile moves".I can comprehend the
>extended futlity pruning but not this.For me as long as standing pat cut off
>is there , futility pruning at frontier is unnecessary,and if it is,it only
>saves the time to make and unmake futile moves.Where does the 60% tree shrinkage
>comes from?Please try to see where my proble is.
>
>Daniel



Your logic seems sound for me. We seem to save only
MakeMove() + UnmakeMove() + Evaluate().

/Matthias.












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