Author: Tony Werten
Date: 23:27:53 11/09/03
Go up one level in this thread
On November 09, 2003 at 07:40:38, scott farrell wrote: >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. No, only when you were wrong. That's the whole point with futility pruning, it only saves nodes when you were wrong. Normal: Make move, goto quiescence, eval>beta, cutoff. go back, unmake move. pruning: "eval" <alpha, skip. You save 1 make move, 1 function call, 1 eval and 1 unmake move but never a node. When you save nodes, it means normal search does not cutoff at that point => eval is not >beta => your assumption that score could never make it to alpha was wrong. Tony > >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.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.