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Subject: Re: Schröder's new web page

Author: Ed Schröder

Date: 10:13:41 12/28/02

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On December 28, 2002 at 12:21:34, Alessandro Damiani wrote:

>
>>>It seems to me that there are two typos in the following code:
>>>
>>>{
>>>   if (remaining_depth > 2
>>>      && king_not_in_check
>>>      && move_is_no_capture
>>>      && move_is_not_giving_a_check) then
>>>       { if (ALPHA < SCORE + MARGIN) reduce depth with 1 }
>>>}
>>>
>>>1) king_not_in_check <=> move_is_not_giving_a_check
>>
>>I interpret "king_not_in_check && move_is_no_capture &&
>>move_is_not_giving_a_check" as My king is not in check and I can't capture any
>>of his material and I can't check his king, so it looks fine to me.
>>
>
>As you say you interpret, as I did. So, something is not clear.
>
>
>>>2) instead of
>>>
>>>       ALPHA < SCORE + MARGIN
>>
>>You have a SCORE below ALPHA and you want to know if it is far enough below
>>ALPHA to warrant a reduction, so you add MARGIN to it to see if it is still
>>below ALPHA. If it is, you reduce. This looks fine to me too.
>>

>We both understand the idea, but formally the condition is wrong, as I showed.

Yes, you were right, please keep on bugging me.

I have changed the page, it looks now:

  if (remaining_depth > 2
      && own_king_was_not_in_check_before_make_move
      && move_is_no_capture
      && move_does_not_check_the_opponent_king) then    // such as Bf1-b5+
       { if (ALPHA > SCORE + MARGIN) reduce depth with 1 }

  SCORE  = The score of the position (material value +
           piece-square value's)

  MARGIN = TABLE [remaining_depth];

  static int TABLE    0,   0,   0, 500, 500, 700, 700, 900,
                    900,1500,1500,1500,1500,1500,1500,1500,
                   1500,1500 ................................ };

======

Ed



>But Ed knows best.
>
>Alessandro



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