Author: Ulrich Tuerke
Date: 07:32:15 04/06/00
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On April 06, 2000 at 00:45:28, Nobuhiro Yoshimura wrote: >On April 05, 2000 at 20:57:30, Robert Hyatt wrote: > >>On April 05, 2000 at 20:54:52, Nobuhiro Yoshimura wrote: >> >>> I am writing a Japanese Chess program using PVS with iterative deeping and >>>hash tables. I often get a fail-low at the root node at the end stage of >>>the game. I would like to know how offten do you get fail-lows in >>>searching the chess game tree and also what kind of bugs are possible to >>>cause many fai-lows. >> >> >>I don't quite understand why you think it is a bug. IE sometimes when you >>go a ply deeper, you discover some threat your opponent has that you simply >>can't defend against, and the score drops. It is not abnormal... > >I just thought that since PVS is a good searching algorithm and is >being used by many chess programmers that it would not produce >many fail-lows that are very bad for search efficincy. I would attribute these fail-lows to your static evaluation as well as to the search. May be you give larger evaluation terms in endings (e.g. passed pawns, square rule, ...) . Consequently your search will produce resulting scores which are spread over a larger region than in middle game. It could be worthwhile to let the window size depend on the stage of the game ? Regards, Uli
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