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Subject: Re: A question about underpromotion danger

Author: Bruce Moreland

Date: 16:07:09 08/04/99

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On August 04, 1999 at 14:55:50, Dann Corbit wrote:

>On August 04, 1999 at 14:09:18, Bruce Moreland wrote:
>>On August 04, 1999 at 12:16:52, Dann Corbit wrote:
>>
>>>As a 'for instance':
>>>
>>>Suppose that on promotion, a program sees that it can promote to a knight
>>>instead of a queen, and get a king fork, taking a bishop, followed by a queen
>>>fork, taking the other bishop.  In such a case, it might evaluate:
>>>   -pawn+knight+bishop+bishop+two_bishop_bonus+(minor positional goo)
>>>verses
>>>   -pawn+queen
>>>and get something a fraction more valuable than a queen.  But down the road I
>>>would rather have the queen than a knight and remove the two bishops.
>>>
>>>How do programs deal with this?
>>
>>You are really saying you'd rather have a queen against two bishops than be a
>>knight up, right?
>Yes.  Especially since it is so much easier to mate with a queen than a knight
>[depending upon what else is on the board of course].
>;-)
>
>Even in the general case that is almost always my preference.  But I think
>pretty much a chess program is just going to do a quick eval and not look 25
>moves ahead where the queen would start to pay dividends.

This is where your positional eval needs to come into play.  If you  have a
queen against two bishops it is possible to get your butt kicked off in some
cases, while in other cases it is an easy win.  Likewise a knight up can either
be easy or hard to win.

bruce



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