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Subject: Re: Futility @ 1/Extended Futility @ 2/Limited Razoring @ 3 = % node reduce?

Author: Stuart Cracraft

Date: 20:02:18 10/19/04

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On October 19, 2004 at 21:11:47, Jeremiah Penery wrote:

>On October 19, 2004 at 19:51:17, Stuart Cracraft wrote:
>
>>On October 19, 2004 at 16:34:32, GeoffW wrote:
>>
>>>Hi Stuart
>>>
>>>Can you clarify what margin thresholds you used and was the distance to the leaf
>>>before or after you made a move ?
>>>
>>>     Geoff
>>
>>Sure. Margins were 3 pawns for futility pruning at depth == 1 (before
>>the makemove), 5 pawns for extended futility pruning at depth == 2
>>(before the makemove), and 9 pawns for limited razoring at depth == 3
>>(before the makemove).
>>
>>In the first two cases, if found to prune, the node simply isn't searched
>>and skipped to the next move. In the last case, if found true, then the
>>depth is decremented for that move only by one additional ply.
>
>Do you know if the conditions are ever being properly triggered?
>
>In a depth 11 search on WAC 175 (a position I picked at random), I have these
>statistics in a modified Crafty with the pruning described below:
>
>Elapsed Time: 28.77, CPU Time: 27.62, CPU Use: 96%
>Root Material Balance: -200, Predicted Moves: 0
>Nodes: 12146603, Evaluations: 9251784, FH%: 97%, NPS: 422k
>EXTENSIONS->
>Threat: 174, Check: 679610, One Move: 21736
>Passed Pawn: 920, Recapture: 24192
>PRUNING->  Futility: 4329693, Razors: 405194
>
>I implemented a variation of the Heinz/DT futility in Crafty (instead of
>returning a static score where pruning happens, I had it drop into qsearch for
>much more accuracy).  I don't know how the node count compares to a regular
>version, or how much the savings for futility is.  I'm sure someone else can run
>a default Crafty with futility on and off and report the exact differences.

Mine (depth 11, wac 175):

10/46  d2d4 53.34   17  4235681 d2d4 d7d5 b1c3 b8c6 e2e4 d5e4 d4d5 c6e5 c3e4 c8f
5
                                d2d4 d7d5 b1c3 b8c6 e2e4 d5e4 d4d5 c6e5 c3e4 c8f
5
11/46  d2d4 131.67   26  8955895 d2d4 d7d5 b1c3 b8c6 e2e4 d5e4 d4d5 c6e5 c3e4 c8
f5 f1b5 c7c6
                                d2d4 d7d5 b1c3 b8c6 e2e4 d5e4 d4d5 c6e5 c3e4 c8f
5 f1b5 c7c6
d2d4 131.67   26  8955895 d2d4 d7d5 b1c3 b8c6 e2e4 d5e4 d4d5 c6e5 c3e4 c8f5 f1b5
 c7c6
                                d2d4 d7d5 b1c3 b8c6 e2e4 d5e4 d4d5 c6e5 c3e4 c8f
5 f1b5 c7c6
nps=68016 ha=22.00% q=66.0% bc=56% br=3.01% mp=139<>117
pawnx=2658 recapx=51744 qcheckx=0 checkx=129985 qfutilx=2374715 onereplyx=8428 m
thrx=14 otherx=1354

Futility/Razor pruning count is only 1354 compared with 5M for Crafty.

Uh, Houston, I think we have something wrong.





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