16 added 55 characters in body edited Jul 30 at 23:19 ajax333221 1,8211616 silver badges3939 bronze badges There are exactly 8 cols The row sum of the empty squares and pieces add to 8 There are no consecutive numbers for empty squares There are exactly 8 cols The row sum of the empty squares and pieces add to 8 There are exactly 8 cols The row sum of the empty squares and pieces add to 8 There are no consecutive numbers for empty squares 15 deleted 8 characters in body edited Aug 25 '16 at 1:49 ajax333221 1,8211616 silver badges3939 bronze badges There are no more than 8 pawns from each color There aren't any pawns in first or last rows In case of en passant square; see if it was legally created (e.g it must be on the `x3` or `x6` row, there must be a pawn (from the correct color) in front of it, and the en passant square and the one behind it are empty) Prevent having more promoted pieces than missing pawns (e.g `extra_pieces = Math.max(0, num_queens-1) + Math.max(0, num_rooks-2)...` and then `extra_pieces <= (8-num_pawns)`), also you should do special calculations for bishops, If you have two (or more) bishops from the same square color, these can only be created through pawn promotion and you should include this information to the formula above somehow The pawn formation is possible to reach (e.g in case of multiple pawns in a single col, there must be enough enemy pieces missing to make that formation), here are some useful rules: it is impossible to have more than 6 pawns in a single column (because pawns can't exist in the first and last ranks) the minimum number of enemy missing pieces to reach a multiple pawn in a single col `B to G 2=1, 3=2, 4=4, 5=6, 6=9 ___ A and H 2=1, 3=3, 4=6, 5=10, 6=impossible6=15`, for example, if you see 5 pawns in A or H, the other player must be missing at least 10 pieces from his 15 captureable pieces if there are white pawns in a2 and a3, there can't legally be one in b2, and this idea can be further expanded to cover more possibilities There are no more than 8 pawns from each color There aren't any pawns in first or last rows In case of en passant square; see if it was legally created (e.g it must be on the `x3` or `x6` row, there must be a pawn (from the correct color) in front of it, and the en passant square and the one behind it are empty) Prevent having more promoted pieces than missing pawns (e.g `extra_pieces = Math.max(0, num_queens-1) + Math.max(0, num_rooks-2)...` and then `extra_pieces <= (8-num_pawns)`), also you should do special calculations for bishops, If you have two (or more) bishops from the same square color, these can only be created through pawn promotion and you should include this information to the formula above somehow The pawn formation is possible to reach (e.g in case of multiple pawns in a single col, there must be enough enemy pieces missing to make that formation), here are some useful rules: it is impossible to have more than 6 pawns in a single column (because pawns can't exist in the first and last ranks) the minimum number of enemy missing pieces to reach a multiple pawn in a single col `B to G 2=1, 3=2, 4=4, 5=6, 6=9 ___ A and H 2=1, 3=3, 4=6, 5=10, 6=impossible`, for example, if you see 5 pawns in A or H, the other player must be missing at least 10 pieces from his 15 captureable pieces if there are white pawns in a2 and a3, there can't legally be one in b2, and this idea can be further expanded to cover more possibilities There are no more than 8 pawns from each color There aren't any pawns in first or last rows In case of en passant square; see if it was legally created (e.g it must be on the `x3` or `x6` row, there must be a pawn (from the correct color) in front of it, and the en passant square and the one behind it are empty) Prevent having more promoted pieces than missing pawns (e.g `extra_pieces = Math.max(0, num_queens-1) + Math.max(0, num_rooks-2)...` and then `extra_pieces <= (8-num_pawns)`), also you should do special calculations for bishops, If you have two (or more) bishops from the same square color, these can only be created through pawn promotion and you should include this information to the formula above somehow The pawn formation is possible to reach (e.g in case of multiple pawns in a single col, there must be enough enemy pieces missing to make that formation), here are some useful rules: it is impossible to have more than 6 pawns in a single column (because pawns can't exist in the first and last ranks) the minimum number of enemy missing pieces to reach a multiple pawn in a single col `B to G 2=1, 3=2, 4=4, 5=6, 6=9 ___ A and H 2=1, 3=3, 4=6, 5=10, 6=15`, for example, if you see 5 pawns in A or H, the other player must be missing at least 10 pieces from his 15 captureable pieces if there are white pawns in a2 and a3, there can't legally be one in b2, and this idea can be further expanded to cover more possibilities 14 deleted 71 characters in body edited Aug 21 '16 at 22:09 ajax333221 1,8211616 silver badges3939 bronze badges There are no more than 8 pawns from each color There aren't any pawns in first or last rows In case of en passant square; see if it was legally created (e.g it must be on the `x3` or `x6` row, there must be a pawn (from the correct color) in front of it, and the en passant square and the one behind it are empty) Prevent having more promoted pieces than missing pawns (e.g `extra_pieces = Math.max(0, num_queens-1) + Math.max(0, num_rooks-2)...` and then `extra_pieces <= (8-num_pawns)`), also you should do special calculations for bishops, If you have two (or more) bishops from the same square color, these can only be created through pawn promotion and you should include this information to the formula above somehow The pawn formation is possible to reach (e.g in case of multiple pawns in a single col, there must be enough enemy pieces missing to make that formation), here are some useful rules: it is impossible to have more than 6 pawns in a single column (because pawns can't exist in the first and last ranks) it is impossible to have more than 5 pawns in `a` or `h` columns the minimum number of enemy missing pieces to reach a multiple pawn in a single col `B to G 2=1, 3=2, 4=4, 5=6, 6=9 ___ A and H 2=1, 3=3, 4=6, 5=10, 6=impossible`, for example, if you see 5 pawns in A or H, the other player must be missing at least 10 pieces from his 15 captureable pieces if there are white pawns in a2 and a3, there can't legally be one in b2, and this idea can be further expanded to cover more possibilities There are no more than 8 pawns from each color There aren't any pawns in first or last rows In case of en passant square; see if it was legally created (e.g it must be on the `x3` or `x6` row, there must be a pawn (from the correct color) in front of it, and the en passant square and the one behind it are empty) Prevent having more promoted pieces than missing pawns (e.g `extra_pieces = Math.max(0, num_queens-1) + Math.max(0, num_rooks-2)...` and then `extra_pieces <= (8-num_pawns)`), also you should do special calculations for bishops, If you have two (or more) bishops from the same square color, these can only be created through pawn promotion and you should include this information to the formula above somehow The pawn formation is possible to reach (e.g in case of multiple pawns in a single col, there must be enough enemy pieces missing to make that formation), here are some useful rules: it is impossible to have more than 6 pawns in a single column (because pawns can't exist in the first and last ranks) it is impossible to have more than 5 pawns in `a` or `h` columns the minimum number of enemy missing pieces to reach a multiple pawn in a single col `B to G 2=1, 3=2, 4=4, 5=6, 6=9 ___ A and H 2=1, 3=3, 4=6, 5=10, 6=impossible`, for example, if you see 5 pawns in A or H, the other player must be missing at least 10 pieces from his 15 captureable pieces if there are white pawns in a2 and a3, there can't legally be one in b2, and this idea can be further expanded to cover more possibilities There are no more than 8 pawns from each color There aren't any pawns in first or last rows In case of en passant square; see if it was legally created (e.g it must be on the `x3` or `x6` row, there must be a pawn (from the correct color) in front of it, and the en passant square and the one behind it are empty) Prevent having more promoted pieces than missing pawns (e.g `extra_pieces = Math.max(0, num_queens-1) + Math.max(0, num_rooks-2)...` and then `extra_pieces <= (8-num_pawns)`), also you should do special calculations for bishops, If you have two (or more) bishops from the same square color, these can only be created through pawn promotion and you should include this information to the formula above somehow The pawn formation is possible to reach (e.g in case of multiple pawns in a single col, there must be enough enemy pieces missing to make that formation), here are some useful rules: it is impossible to have more than 6 pawns in a single column (because pawns can't exist in the first and last ranks) the minimum number of enemy missing pieces to reach a multiple pawn in a single col `B to G 2=1, 3=2, 4=4, 5=6, 6=9 ___ A and H 2=1, 3=3, 4=6, 5=10, 6=impossible`, for example, if you see 5 pawns in A or H, the other player must be missing at least 10 pieces from his 15 captureable pieces if there are white pawns in a2 and a3, there can't legally be one in b2, and this idea can be further expanded to cover more possibilities 13 added 185 characters in body edited Sep 16 '13 at 20:09 ajax333221 1,8211616 silver badges3939 bronze badges 12 added 270 characters in body edited Jul 4 '13 at 16:07 ajax333221 1,8211616 silver badges3939 bronze badges 11 added 218 characters in body edited Jun 24 '13 at 19:36 ajax333221 1,8211616 silver badges3939 bronze badges 10 too lazzy to sign in edited Jun 21 '13 at 23:42 ajax333221 1,8211616 silver badges3939 bronze badges 9 too lazzy to sign in edit approved Jun 21 '13 at 23:42 8 added 111 characters in body edited Jun 20 '13 at 19:32 ajax333221 1,8211616 silver badges3939 bronze badges 7 deleted 11 characters in body edited Nov 13 '12 at 17:24 ajax333221 1,8211616 silver badges3939 bronze badges 6 added 15 characters in body edited Nov 13 '12 at 17:05 ajax333221 1,8211616 silver badges3939 bronze badges 5 added 582 characters in body edited Nov 11 '12 at 19:28 ajax333221 1,8211616 silver badges3939 bronze badges 4 added 128 characters in body edited Nov 9 '12 at 23:16 ajax333221 1,8211616 silver badges3939 bronze badges 3 added 1190 characters in body edited Nov 8 '12 at 19:45 ajax333221 1,8211616 silver badges3939 bronze badges 2 deleted 10 characters in body edited Nov 2 '12 at 22:46 ajax333221 1,8211616 silver badges3939 bronze badges 1 answered Nov 2 '12 at 22:41 ajax333221 1,8211616 silver badges3939 bronze badges Post Made Community Wiki by ajax333221 occurred Nov 2 '12 at 22:41