Author: Uri Blass
Date: 00:41:01 02/04/05
I find that there are some illegal positions in nalimov tablebases like the following position because there is no possible last move of white. [D]3K4/8/8/3R4/3kR3/8/8/8 b - - 0 1 Note that the following position is legal(last move of white could be under promotion to a rook) [D]kR1K4/8/R7/8/8/8/8/8 b - - 0 1 I wonder if somebody cared to count the number of legal positions with 6 or less pieces. A position with 4 pieces is illegal if it cannot be reached from position that is not obviously illegal of 5 piece or less pieces so it is possible to count the number of 4 piece positions that can be reached from positions of 5 or 4 pieces. I am not sure if all of them are legal but I cannot think about an example when a position with 4 pieces is illegal and can be reached from illegal 5 piece position. note that it is different with 5 piece position and 6 piece position and here is an example. [D]6k1/8/8/8/8/8/3P1P2/4B1K1 w - - 0 1 illegal can be reached from [D]6R1/5k2/8/8/8/8/3P1P2/4B1K1 b - - 0 1 also illegal. Uri
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