Author: José de Jesús García Ruvalcaba
Date: 09:51:20 06/10/99
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On June 10, 1999 at 11:30:59, William Bryant wrote: >Good luck to all moderator candidates. And now for something completely >different ... :) > >A couple of questions. > >I re - de -bugged my search after adding the killer heuristic and noted >that it does better in most positions - _but_ - some positions seem to do much >worse. I suspect this continues to be a move ordering issue. > >For example, >on the endgame position FINE 70, >without the killer heuristic it fails high on ply 26 finding Kb1 in about 3 1/2 >minutes, but with the killer heuristic, at about ply 20 or 21 there is a >noticable slow down in time to achieve the next ply. > >Are there some positions or phases in the game where the killer moves are not >needed and should be avoided? > Most likely yes. One of the difficult tasks is to clearly identify those positions with some kind of cheap test. José. >Is this a bug ( or feature ), and most likely due to move ordering? >If so, why apparent only after ply 20. > >I noted that on this position the history heuristic begins to add up to some >larger numbers. Is there a point where the history table should be reset or >reduced within a search rather than only at the start of each search? > >Lastly, I'm thinking of adding attack tables to speed up the search. At >present, I think they would be helpful in identifying all the squares that a >pawn or piece can attack when placed at a particular location which would speed >up the InCheck() function. Where else would these tables be helpful? Since I >plan to use 64 bit long long values and logical 'and' those with a square mask, >this will return a boolean value about whether the piece attacks. Can they be >used in move generation? Other locations? Any comments, pointers, or referances >to articles or source code would be appreciated. > >William >wbryant@ix.netcom.com
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