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Subject: Re: futility pruning?

Author: scott farrell

Date: 04:40:38 11/09/03

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On November 09, 2003 at 04:55:40, Matthias Gemuh wrote:

>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().

I think you are wrong, you save:

MakeMove() + UnmakeMove() +alphaBeta()+ qSearch()+ stand-pat+ Evaluate().

qsearch of course can be a few plies also.

I think I do it after makeMove so its more accurate, I might try before makeMove
- and see what happens. But I am not sure if I can work out if its a checking
move too easily unless I makeMove().

Scott
>
>/Matthias.



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