Author: blass uri
Date: 14:20:33 11/26/99
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On November 26, 1999 at 11:45:55, Heiner Marxen wrote: >On November 25, 1999 at 21:16:19, leonid wrote: > >>On November 25, 1999 at 17:58:27, Heiner Marxen wrote: >> >>>>For me the fact of recognition os the check is almost as >>>>time consuming as legality of all the pieces beside the king >>> >>>If you know the last move, which leads to the position in question, >>>you need not search much to find the checking piece(s). With the >>>exception of e.p. and castling moves, there are just two chances: >>>(d) the last moved piece may give a direct check from its target square >>>(i) the last moved piece may have discovered a check on its source square >>> >>>(i) is possible only, if your king´s square is related to the last pieces >>>from square: on same row, column or diagonal. That can be detected fast. >>>For (d) similar geometric considerations are possible. >>> >>>Heiner >> >>Very good consideration and very well explained! I must look into it. The only >>inconvience here I see in two facts: >> >>1) Once mistake about the position of the king could lead to the accumulation >>and mistakes and collapse of entire game. When on each new position all the data >>about the fire against the king is recollected, such domino effect is excuded. > >Ok, but that would be a bug, which has to be corrected. Therefore, I have >a debug mode, which before and after each make or unmake move checks all >redundant data for validity. Can be *very* helpful. Recommended. > >>2) All the data that recognize the legality of the moves, beyond the moves of >>the king, will be not available. This data is recollected in the same procedure >>that recognize if the king is under the fire. > >Therefore my program generates strictly legal moves, only. The way I do it, >it does not cost more than it gains. And the additional redundant data >(attack data for all squares) does help a lot at other places. >But that is different for every program, there is no single best way to do it. > >Heiner Marxen heiner@drb.insel.de http://www.drb.insel.de/~heiner/ How many nodes(legal moves) does your program search per second? I remember that you developed a good mate searcher. Did you develop a chess program for playing or only for finding mate? Maybe the answer is in the link but the site http://www.drb.insel.de/~heiner/ is probably down. Uri Uri
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