Author: Benny Antonsson
Date: 01:54:24 01/29/02
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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 Which programs finds it ?
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