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

Author: Jeremiah Penery

Date: 22:29:54 10/19/04

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On October 19, 2004 at 23:02:18, Stuart Cracraft wrote:

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

I remember when I tried implementing this that I had some strange issues that
took a while to work out.  Some things in the DT implementation have to be
changed to match the structure of your program, and it's very easy to have
mistakes in those changes.

I think you've posted the code before, but if you could do so again (or better,
email it to me), I can try to take a look at it.  I can't make promises, but
maybe I can come up with something. :)

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