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Subject: Re: Extensions

Author: Andrew Williams

Date: 01:53:26 04/23/04

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On April 23, 2004 at 03:37:38, Jeff GAZET wrote:

>Good morning,
>
>i'm trying to add extensions to my engine. I'm using a classical alphabeta
>function :
>int alphabeta(int depth, int alpha, int beta)
>depth is dicreased 1 by 1 :
>eval=-alphabeta(depth-1,-beta,-alpha);
>
>At the beginning at the function alphabeta(), if king is incheck, i do
>++depth. This works fine.
>
>In the main move loop, if do a ++depth on a promoting move, juste before
>calling -alphabeta... the engine searches for ever when the first promoting
>move is found. Then, if i add "if depth<1" or <2, i don't see any
>improvment.
>

Maybe a stupid question, but you do remember to do depth-- after your call to
alphabeta(..)? Otherwise you could be extending *every* move in positions where
a promotion is available.


>I don't understand how engines like GnuChess can write : depth+=DEPTH when
>extending.
>(DEPTH is 12).
>
>Could someone give me some explanations, please ?
>
>Regards.

Andrew



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