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Subject: Re: hanging pieces in rebel

Author: Robert Hyatt

Date: 13:31:17 01/16/04

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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.

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...

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