Author: Tony Werten
Date: 05:03:44 12/30/02
Go up one level in this thread
On December 30, 2002 at 07:08:27, Ed Schröder wrote:
>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)
>
>For free-style pseudo code it is defendable, maybe in more c-code style would
>make it more clear?
>
> { if (ALPHA > SCORE + THREAT &&
> ALPHA < SCORE + THREAT + MARGIN) -> reduce depth with one ply. }
I don't get this one.
I would expect:
1) score+threat>alpha : OK you have some threat, don't reduce
2) score+threat+margin>alpha: You have a threat, if you win it and and get some
positional advantage you could end up above alpha so to be safe don't reduce.
3) score+threat+margin: No (good) threats, even with something added you're
still not close to alpha so reduce.
You seem to have swapped the reduction conclusions from 2 and 3. What's the idea
? Is it that 3 will be reduced anyway later on, and you want to add some
reductions to 2 ?
Cheers,
Tony
>
>ALPHA=100
>SCORE=90
>THREAT=0
>MARGIN=20
>
>-> reduction
>
>ALPHA=100
>SCORE=60
>THREAT=0
>MARGIN=20
>
>-> no reduction
>
>Ed
>
>
>>Martin
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