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Subject: Re: Extensions

Author: Jeff GAZET

Date: 03:01:05 04/23/04

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>>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.

Yes, depth is dicreased each call to alphabeta :
eval=-alphabeta(depth-1,-beta,-alpha);

>>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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