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Subject: Re: Rebel's long checks concept in QS

Author: Harald Lüßen

Date: 11:53:17 01/23/04

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On January 23, 2004 at 14:22:28, milix wrote:
>I tried to implement the long checks idea of Ed Schröder
>(http://members.home.nl/matador/chess840.htm#QS) but not worked for me.
>Maybe my QS is not implemented correctly to have this checks concept but I can't
>figure it by myself. I wish for some help here (maybe from Ed himself) :-)
>
>In my main search, before I enter the QS I set the variable MAX_CHECKS_DEPTH to
>2.
>
>My quiescent in pseudo code:
>
>quiescent(alpha, beta)
>{
>   save the MAX_CHECKS_DEPTH
>   score = full_evaluate()
>   if (score < alpha) return score

Change the last line to
if (score >= beta) return beta;

>   if (score > alpha) alpha = score
>
>   if (side_to_move_is_in_check)
>      generate_legal_moves()
>   else if (MAX_CHECKS_DEPTH > 0)
>      generate_good_equal_captures_queenpromotions_and_checks()
>   else generate_good_equal_captures_queenpromotions()
>   sort_the_moves()
>
>   for each move in the list {
>      make_the_move()
>      score = - quiescent(-beta, -alpha)
>      undo_the_move()
>      restore MAX_CHECKS_DEPTH
>      if (score < alpha) return score;

And again
if (score >= beta) return beta;

>      if (score > alpha) alpha = score;
>   }
>   MAX_CHECKS_DEPTH = MAX_CHECKS_DEPTH - 1
>
>   return alpha
>}
>
>Thanks in advance!

Harald



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