Author: Ulrich Tuerke
Date: 08:42:45 05/22/03
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On May 22, 2003 at 11:16:18, David H. McClain wrote: >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 >> >>> The >>>all the other underpromotions will return alpha and thus ignored. >>> >>> José C. > >Jose, > >No, everyone is not doing this. At least I am not. Admittedly I have played >only one game where an underpromotion was an absolute necessity to regain tempo >and obtain a "check" to prevent a checkmate to the other side. This was to a >knight promotion rather than a Queen. And the game was eventually won with the >knight promotion. I'm sure others have witnessed this on occasion also. > >Don't ask me to find and post this game. I don't know where or if I have it but >I simply regarded it as "the program knows best" and let it go at that. The >program was correct.......... I don't think that we are talking about omitting under-promotions but about move-ordering solely. When generating moves in full search, I sort promotions like 1. queen 2. knight 3. rook 4. bishop That's because rook or bishop promotions will only very rarely generate a cut in a case where the queen doesn't. Usually, the queen will do anyway. However, the knight may be a serious alternative to a queen promotion. Therefore, I prefer it to rook and bishop. This way, you can't miss a win by knight promotion. In quies search, I omit (3) and (4). Uli
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