Author: Ricardo Gibert
Date: 09:34:42 10/18/00
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On October 18, 2000 at 10:10:51, Dieter Buerssner wrote: >I am trying to find a relatively fool proof way, to detect, if >an endgame with a rook pawn (or a doubled rook pawn) and the wrong >bishop against a lonely king, is a draw. Ideally I would like an >algorithm, that only needs the loosing king square (perhaps the >winning king square), the pawn square and the side to move, and it >should detect, if this is a draw. > >I tried so far, to only use the pawn square and the losing king >square. When the loosing king is closer to the corner, than the >pawn, it is a draw. When the distance is the same, the side to move >will be better. But this does not allways work. I think, it would be better, to >be certain of the draw, and in compilcated cases, that can not be decided, give >a small positive score to the bishop side. Have you any ideas about a simple >algorithm? Would it be different, when the rook pawn >is doubled? And when the losing side has a pawn, that say is not too advanced? > >One nice example from Tarrasch "Das Schachspiel": > >[D] 8/4k3/8/7P/4B3/5K2/8/8 w - - 0 1 > >White wins with 1.h6 Kf7 2.Bh7 > >Which programs, that have knowledge about this sort of endgame will >show a winning score without search and TBs? I tried this with >Crafty, and it shows a draw score up to depth 6. This is of course >problem in this game, because it only takes a fraction of a second >to reach depth 7, but it might be dangerous, when the position >is reached in the search. > >Regards, >Dieter Here are a couple more positions: [D]8/8/5k1P/7B/8/8/8/K7 b - - 0 0 [D]5k2/8/7P/3B4/8/8/8/K7 b - - 0 0 I'm sure Bob knows all of these. This type of a position happens frequently, so if he had a bug in the code handling this, he would have noticed it long ago. The algorithm to determine whether this type of position is drawn is quite simple. With the h-pawn, Black draws if the K can get into the four corner squares g7,g8,h7,h8. Otherwise, the outcome is not assured. Note, it is not enough for the King to get in front of the pawn as the following position illustrates: [D]6K1/8/7k/7P/8/5B2/8/8 w - - 0 0
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