Author: Nobuhiro Yoshimura
Date: 17:14:41 04/06/00
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On April 06, 2000 at 10:32:15, Ulrich Tuerke wrote: >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 Thanks. As you guessed, I assign large values in positional evaluation. I will try to chagne the window size in the root node depending on the stage of the game.
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