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Subject: Re: Reduction 2b and 2c

Author: Dave Gomboc

Date: 11:52:30 12/30/02

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On December 30, 2002 at 05:53:16, Martin Giepmans wrote:

>On December 30, 2002 at 05:30:45, Ed Schröder wrote:
>
>>As it seems I have completely mishandled explaining Reduction 2b and 2c, I have
>>corrected things.
>>
>>http://members.home.nl/matador/chess840.htm
>>
>>Click on the blue "update" picture, it will move you directly to the changes
>>made. That will be standard procedure from now on in case of errors.
>>
>>if (remaining_depth<=x && remaining_depth>1) then
>>   { if (ALPHA < SCORE + THREAT)          -> do not reduce
>>     if (ALPHA < SCORE + THREAT + MARGIN) -> reduce depth with one ply. }
>>
>>  SCORE  : score of EVAL
>>  THREAT : Queen=900, Rook=500, Bishop=300, Knight=300, Pawn=100
>>  MARGIN : TABLE [remaining_depth];
>>
>>  static int TABLE[]= { 00,00,10,15,20,25,25,25,25,25,25,25,25,25,
>>                        25,25,25,25,25,25,25 ........... };
>>
>>The idea is, if SCORE+THREAD are not going to make it to ALPHA, but with an
>>extra small MARGIN it will then reduce the depth. I can't remember the speed-up
>>this reduction gave.
>>
>>====
>>
>>Ed
>>
>>PS, the "faulty stuff" plus Uri's correction is maybe worth a try, who knows :)
>
>The < in the second formula should be > ?
>Otherwise the two formula's together don't make sense.
>(if the first is true, the second is also true)
>
>Martin

I think it's:

if ((remaining_depth <= x) && (remaining_depth > 1)) then
   { if (ALPHA < SCORE + THREAT)          -> do not reduce
     *else* if (ALPHA < SCORE + THREAT + MARGIN) -> reduce depth by one ply. }

Dave



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