Author: Ricardo Gibert
Date: 08:11:00 07/09/99
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On July 09, 1999 at 04:47:47, David Blackman wrote: >On July 09, 1999 at 02:58:46, Richard A. Fowell (fowell@netcom.com) wrote: > >>On July 08, 1999 at 21:59:17, Jonathan Goldstein wrote: >> >>>After experimenting with board representaions for a few months, >>>I found a representaion in which the move generator is slightly >>>slower than rotated bitboards in the middlegame, but factors >>>of 2 to 5 faster in the endgame (on a 32-bit processor). I >>>decided to go with this representation, but it does have one >>>drawback: Each side cannot have more than 8 of any piece. >>> >>>Is this a problem for normal (not wild) chess? At first I >>>thought it couldn't possibly be, but then I considered if the >>>engine ever gets fast enough to search 15 ply, and one of the >>>extensions has the eighth pawn promoted, it could happen. Am I >>>just being rediculous? :) >>> >>>-Jon >> >>Your in good company - some of the top commercial programs >>can't handle this, either. >> >>It's a theoretical problem, but not much of a practical one. >>In my 1300 tournament games, the largest number of any piece >>I saw was five (bishops, as it turned out - my opponent was >>trying to shame me into resigning). >> >>Maybe someone with a millionbase can comment on the maximum >>number of each type of piece seen? >> >>-Richard > >It probably won't happen over the board, but still could happen >in the lookahead search. Probably this won't happen on critical >lines in the search though, so just code it so it doesn't crash. >Maybe pretend that any move that brings in the 9th Queen >(or other piece) is illegal. Coding 9 queens as being illegal sounds like excellent practical advice. I seriously doubt it can adversely effect your program. Even if it did. It is so rare, you stand to gain more than you lose. The speed up for endings is intriguing. At the very least, a worthy experiment. I would worry more about the slight slow down in the middle game. The "before the endgame, the gods have placed the middlegame" crap might hurt you. I hope it works. Good luck.
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