Author: Alexander Kure
Date: 01:08:24 01/29/02
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On January 29, 2002 at 03:36:56, Benny Antonsson wrote: >On January 29, 2002 at 03:12:08, Gerd Isenberg wrote: > >>On January 28, 2002 at 23:20:45, James Swafford wrote: >> >>> >>>Does anybody do this? I just implemented a passed pawn extension >>>that extends the depth by 1 if the move was a pawn move to the >>>sixth or seventh rank, and that pawn is not blocked by a pawn of >>>the opposite color. >>> >>>The results are pretty disappointing. It really blew up my search. >>>I decided to modify the implementation by saying only looking for >>>pawn pushes to the seventh rank, and it still can blow up pretty >>>bad. >>> >>>Obviously most over the board positions would not trigger this >>>extension, but there are some that would blow up the search like >>>mad. >>> >>>One thought I had is to use a fractional extension scheme. That >>>may help, but I'd like to know if anybody else does this extension, >>>and what mechanisms they have in place to keep the search bloat >>>under control. >>> >>>It's interesting to note that Bruce lists five different extensions >>>on his (excellent) web page; he hasn't actually written about any of >>>them yet, but passed pawn isn't even listed. Hmm... >>> >>>Any ideas or comments? >>> >>>-- >>>James >>I extent passed pawn pushes to fifth, sixth and seventh rank fractionally. The >>amount of extent depends on the number of passed pawn the side to move has, and >>of the rank of course. I also consider GameState - in Middlegame i extend a >>little more than in Endgames or Pawnendings. And i also extend captures a little >>more, which leave a new passer on board, which may help in positions like this: >> >>[D] 8/pR4pk/1b6/2p5/N1p5/8/PP1r2PP/6K1 b - - bm Rxb2 >> >>Gerd >Does black win with this move ? It seemes to me the line would be something >like: >1...Rxb2 2.Nxb2 c3 3.Rxb6! axb6 4.Nd3 Actually 3...c4!! 4.Rb4 a5!! is the winning move sequence. Greetings Alex
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