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Subject: Re: hanging pieces in rebel

Author: rasjid chan

Date: 10:22:48 01/17/04

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On January 17, 2004 at 12:33:53, Robert Hyatt wrote:

>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.  :)

Of course I cannot be too serious. My program is far far away.




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