Author: José Carlos
Date: 04:16:26 05/22/03
Go up one level in this thread
On May 22, 2003 at 07:08:11, Uri Blass wrote: >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 This can happen if you don't have a transposition table. If you have it, all underpromotions followed by the capture of the promoted piece will get a hit in the hash table and there's no need to search further. But it is not the question of the original poster, if I understand him correctly. José C.
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