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Subject: Re: Unnecessary Underpromotions

Author: Uri Blass

Date: 06:06:24 05/22/03

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On May 22, 2003 at 08:41:56, Ulrich Tuerke wrote:

>On May 22, 2003 at 06:08:47, José Carlos wrote:
>
>>On May 22, 2003 at 01:01:38, Robin Smith wrote:
>>
>>>Often programs will underpromote a pawn in situations where they think capturing
>>>the (under)promoted piece is still the best reply. Can anyone give an example
>>>from an actual game where this underspromotion cost the computer a 1/2 point?
>>>
>>>Robin
>>
>>  I can't recall any game with this problem, but it's really easy to fix. I
>>simply order the promotions so that promoting to queen gets searched first.
>
>Isn't everybody doing this anyway ?
>Uli

I do it and I strongly believe that shredder does it
but it is not enough to prevent the problem.

Movei does not use hash tables for pruning and I
think that it may be interesting to read an explanation
for the behaviour of shredder or another program
that considers c1R as best.


I think that in order to prevent the problem a program
can ask itself if an underpromotion makes sense before
considering it and I plan to add it in the future

I do not need hash tables and killer moves
are enough for it.

I simply need to tell the program that if the killer move of
queen promotion is capturing it then it should not consider underpromotions.

Uri



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