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Subject: Re: underpromotion to rook

Author: José Antônio Fabiano Mendes

Date: 11:25:08 04/25/00

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On April 24, 2000 at 23:15:23, Robert Hyatt wrote:

>On April 24, 2000 at 22:34:28, Dann Corbit wrote:
>
>>On April 23, 2000 at 18:13:42, Robert Hyatt wrote:
>>
>>>On April 23, 2000 at 17:15:52, Michael Fuhrmann wrote:
>>>
>>>>Why would a program ever underpromote to a rook? Saw Crafty do this recently.
>>>>(In this particular case, it had no impact on the outcome of the game.)
>>>
>>>
>>>1. it is necessary at times.  IE if you promote to queen, you stalemate your
>>>opponent.  if you promote to rook, you can still win without stalemating him.
>>>
>>>2.  In the case of chess engines, it is pretty common to see this.  The most
>>>common reason is that the =R is not a check, when the =Q is a check, or the
>>>rook allows fewer checks later in the tree.  So by promoting to a rook, it
>>>avoids some tactic that it really can't avoid...  IE this is a horizon effect
>>>situation..
>>
>>Are there any cases where you would promote to bishop or rook to achieve
>>stalemate for yourself?  (e.g. you are far behind in material (say down two
>>queens or more), and the only legal move is the pawn promotion or something of
>>that nature)
>
>
>Sounds hard.. but I'll bet there is a problem composer out there that might
>construct such a position...

http://www.xs4all.nl/~timkr/chess2/minor.htm  [comprehensive!]



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