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Uri Blass

Joined: 08 Mar 2006
Posts: 6016
Location: Tel-Aviv Israel

Post subject: Re: question about symmertic evaluation    Posted: Wed May 23, 2007 10:04 pm

bob wrote:
Gerd Isenberg wrote:
One idea is to avoid the asymmetrical arithmetical shift right 3 at all and to mul all other eval aspects by 8. You may add 7 if the value to shift arithmetical right 3 is negative, but this is of course more expensive.
 Code: symmetrical arithmetical shift right 3 ::= (x + ((x>>31)&7)) >> 3
or with respect to the value range:
 Code: symmetrical arithmetical shift right 3 ::= (x + ((unsigned)x>>29)) >> 3

The common approach seems to score and aggregate from white resp. black point of view and keep both values in evalScore[2] to divide both before the final difference for color's point of view:
 Code: posEval = (evalScore[color]>>3) - (evalScore[color^1]>>3);

Gerd

I'd be willing to bet that a plain divide will not noticably affect his overall search speed. And it will solve this correctly.

thanks

It seems that replacing some >> by / solves the problem
of anti-symmetric evaluation and now at least for the wac positions my evaluation is symmetric between white and black(did not check symmetry between left and right)

Uri
 Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First
Subject Author Date/Time
Uri Blass Wed May 23, 2007 7:53 pm
Uri Blass Wed May 23, 2007 8:45 pm
Gerd Isenberg Wed May 23, 2007 8:46 pm
Uri Blass Wed May 23, 2007 9:04 pm
Robert Hyatt Wed May 23, 2007 9:51 pm
Re: question about symmertic evaluation Uri Blass Wed May 23, 2007 10:04 pm
Gerd Isenberg Wed May 23, 2007 10:09 pm
Robert Hyatt Thu May 24, 2007 12:01 am
Gerd Isenberg Thu May 24, 2007 7:37 am
H.G.Muller Thu May 24, 2007 8:06 am
Gerd Isenberg Thu May 24, 2007 9:24 am
H.G.Muller Thu May 24, 2007 10:39 am
Gerd Isenberg Thu May 24, 2007 11:36 am
H.G.Muller Thu May 24, 2007 11:55 am
Gerd Isenberg Thu May 24, 2007 7:46 pm
Robert Hyatt Thu May 24, 2007 8:18 pm
Gerd Isenberg Thu May 24, 2007 8:55 pm
Uri Blass Fri May 25, 2007 10:44 am
Gerd Isenberg Fri May 25, 2007 6:28 pm
Uri Blass Fri May 25, 2007 7:42 pm
Gerd Isenberg Fri May 25, 2007 8:00 pm
Robert Hyatt Thu May 24, 2007 8:13 pm
Gerd Isenberg Thu May 24, 2007 8:33 pm
Robert Hyatt Sat May 26, 2007 1:05 am
Gerd Isenberg Sat May 26, 2007 7:18 am
Robert Hyatt Sat May 26, 2007 5:08 pm
Robert Hyatt Sat May 26, 2007 5:25 pm
Gerd Isenberg Sat May 26, 2007 6:23 pm
Robert Hyatt Sun May 27, 2007 2:48 pm
Steven Edwards Thu May 24, 2007 3:42 am
Robert Hyatt Thu May 24, 2007 8:20 pm
Robert Hyatt Wed May 23, 2007 9:50 pm
William H. Rogers Fri May 25, 2007 7:48 pm
Uri Blass Sat May 26, 2007 11:38 am
H.G.Muller Sat May 26, 2007 2:07 pm
Vincent Diepeveen Sat May 26, 2007 7:27 pm
Gerd Isenberg Sat May 26, 2007 8:20 pm
Uri Blass Sat May 26, 2007 9:29 pm

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