Author: Uri Blass
Date: 04:08:11 05/22/03
Go up one level in this thread
On May 22, 2003 at 06:35:27, José Carlos wrote: >On May 22, 2003 at 06:14:01, Uri Blass 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. The >>>all the other underpromotions will return alpha and thus ignored. >>> >>> José C. >> >>It is possible to fix but it is not so easy to fix because the other promotion >>may leas to different extensions and different score. >> >>Uri > > > If I understand correctly the original post, we're talking about the scenario >where the program thinks that capturing the promote piece is the best move, so >it randomly promotes any piece, being sure the opponent will capture. Then, it >turns that not capturin the promoted bishop leads to a draw in some extrange >ending. > If I order my moves to analyze the queen promotion first, get back a score and >only then analyze the underpromotions, in the mentioned scenarios all other >promotions will get the same score, exactly the same as the opponent will always >capture the piece in the tree. > Then, first searched move is played. Problem solved. > > José C. The assumption that the moves will get the same score is not always correct. For example the program may extend more promotion for knight with a check so it may be searched deeper and another option is that promotion to queen is extended and searched to bigger depth or promotion not to queen is search to reduced depth. Uri
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