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Subject: Re: about in_check()

Author: JW de Kort

Date: 14:11:11 06/14/03

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On June 14, 2003 at 10:30:58, Magoo wrote:

>I did some tests last night, replacing my in_check() function with attack
>tables, my thought was that it would be faster, but the result was not that
>good, ok i did a fast hack, scanning the whole board because i dont have piece
>lists, but my previous x-ray in_check function was huge. But now im wondering if
>attack tables (implemented with piece lists) are that much better than x-ray.
>
>You have to check all pieces, = 8 pieces (king checks).
>You have to check if pawns are promoted...  = x pieces.
>Check two squares in front of the king.
>
>And of course, sometimes you have to do some tracing.. (sliding pieces).
>In the opening, middlegame there are usually pieces near the king, so the x-ray
>based in_check only has to trace a few directions.
>This got me thinking that the difference between the two isn't so big, am i
>correct? maybe attacks are a few % faster?

Hi,

my in check is also a time consuming process. But is it absolutely necessery?
Maybe it is possible not to check for check at all and just check if a capture
removes the king one ply later. I have not tried this idea but maybe it is
faster then using an in check.

Also i'am thinking of implementing attack tables in my 0x88 program but i have
not found a fast approach. Ant tips?>

regards

Jan Willem




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