Author: James T. Walker
Date: 06:27:55 01/29/02
Go up one level in this thread
On January 29, 2002 at 04:08:24, Alexander Kure wrote: >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 [D]8/pR4pk/1b2p3/2p3p1/N1p5/7P/PPr3P1/6K1 b - - 0 1 This is the unedited (actual game)position according to the text. Fritz 7 finds the key move in 26 seconds on my 1.4G AMD. Also Fritz 7 says the 4. Nxc4 offers more resistance but the outcome is the same.
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