Author: Robert Hyatt
Date: 09:33:53 01/17/04
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On January 17, 2004 at 02:38:24, rasjid chan wrote: >On January 16, 2004 at 16:31:17, Robert Hyatt wrote: > >>On January 16, 2004 at 12:07:00, Tord Romstad wrote: >> >>>On January 16, 2004 at 10:02:39, Robert Hyatt wrote: >>> >>>>I would worry about overflow there. >>>> >>>>IE e4 could be attacked by pawns on d3 and f3, a bishop at d5 with a queen >>>>behind it (4 so far), plus two rooks and two knights. That's 8. It just >>>>overflowed to zero. Not to mention the promotion problems where there is a >>>>third knight or bishop or second queen... >>> >>>It is not so dangerous if you are just a bit careful about where and how >>>you use the information. I use it mostly in the evaluation function, in >>>order to compute stuff like mobility, space and king safety. That one >>>or two squares on the board are evaluated incorrectly once every hundred >>>nodes or so usually does not have any catastrophic consequences. >>> >>>You are of course right that an SEE based on this simple kind of attack >>>tables is not reliable enough to be used to replace a qsearch. For this >>>purpose, I use a much slower and more accurate SEE. >>> >>>Tord >> >>I was more worried about the actual overflow. IE if this is a char, 8 attackers >>appears to be zero. If it is packed into a word, then 8 attackers wraps into >>the next char to the left and corrupts that... > >I think there is no overflow. His BIT0 is the LSB. 8 attacker overflows to >pawn attacking so almost it will be true. having 2 queen almost mean game >decided. Extra Knights or Bishop has other simple solution. The game might not be so decided if your extra queen screws up evaluation and capture analysis. :)
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