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Subject: Re: How to evaluate endgames when one side has no pawns?

Author: Andrew Dados

Date: 18:57:22 11/05/98

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On November 05, 1998 at 21:32:44, Robert Hyatt wrote:

>On November 05, 1998 at 09:47:34, Andrew Dados wrote:
>
>>     Suppose somewhere deep in the search I get reduction to B vs 2P ending...
>>what value
>>should I assign to it? Side with Bishop can't win - so draw for side with 2P at
>>minimum... If I assign  2 *P value then my program will sac Knight for Pawn in
>>B+P vs N+2P...rarely sensible .    What should my eval return in B vs P and B vs
>>2P ?
>>
>>  Andrew  .....(I better get those tablebases working :)
>
>
>simple answer:  if one side can't win, set the upper bound on the score
>for that side to 0.  Then, when you trade into a B vs pp ending, you simply
>say (assuming B=white) score=Min(score,0);  Then you let the two pawns possibly
>drag the score < 0, but you are sure you don't let the B pull the score above
>zero.
>
>In my eval, I recognize two cases:  white can't win and black can't win.  And
>I limit the score so that if white can't win, the score will *never* go above
>zero, and if black can't win, the score will never go below zero...  If both
>are true, we have a draw of course.  :)


  Yeah... this is what I did so far... However simple bounding like that has the
danger of trading into N vs P where N vs 2P could be reached - since those 2
positions will return same =draw= value...now I set minimum to draw +
Pawn_nr*0.3... primitive, but program cares about those pawns :)
Andrew



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