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Subject: Re: futility pruning?

Author: Daniel Shawul

Date: 00:53:24 11/09/03

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>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



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