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Subject: Re: about in_check()

Author: Anthony Cozzie

Date: 08:46:34 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?

Could you explain what you are doing? I was under the impression (and it seems
to work in Zappa) that in_check() is simply:

Get_All_Bishop_Moves(KingSquare), see if there are enemy Bishops/Queens at the
tips.
....
etc.

I tried writing an is_check(Position, Move) once, but it turned out to be too
annoying.



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