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Subject: Re: a difficult (?) R+B vs. R evaluation

Author: Jeremiah Penery

Date: 21:18:10 12/07/02

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On December 07, 2002 at 23:16:13, Robert Hyatt wrote:

>On December 07, 2002 at 22:11:01, Mike S. wrote:
>
>>In a WinBoard match game Delfi 3.2 - Crafty 18.15, the following position
>>occured before the 92nd move, after Crafty allowed it's last pawn to be
>>exchanged (maybe that was forced, though  don't think it was, didn't analyse
>>it):
>>[D]R7/3b1k2/8/6R1/4r2K/7P/3r2P1/8 w - - 0 92
>>Crafty, but also other engines, evaluate that position with a *big* advantage
>>for black, sometimes up to -2.x. No combination involved (the material balance
>>didn't change the next 80 moves).
>
>If Crafty says black is winning, something is broken as there is specific
>code to handle that particular case (one side is a minor piece up but with
>no pawns it has no chance of winning even if the opponent didn't have any
>pawns left...
>
>I'll look to see if I broke something...  although 18.15 might be old enough
>that the fix was not in...

EvaluateWinner() in Crafty is only called when (TotalWhitePieces < 13 &&
TotalBlackPieces < 13).  In the given position, I think that is not the case -
black has exactly 13.  Therefore, the position is not recognized.



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