h#6
8/8/7Q/7k/2R5/1r6/8/K7 b - - 0 1
- Kxh6 Ka2 Rb7 Ka3 Rf7 Kb4 Kg7 Kc5 Kf8 Kd6 Ke8 Rc8#
pure model ideal self-block nocheck
Note: the side to move is in check in the diagram; the solution begins with a capture.
5 pieces.
8/8/7Q/7k/2R5/1r6/8/K7 b - - 0 1
pure model ideal self-block nocheck
Note: the side to move is in check in the diagram; the solution begins with a capture.
4kQ2/7R/8/8/8/8/6r1/1K6 b - - 0 1
pure model ideal mirror switchback
Note: the side to move is in check in the diagram; the solution begins with a capture.
8/8/7Q/7k/1r1R4/8/8/K7 b - - 0 1
Note: the side to move is in check in the diagram; the solution begins with a capture.
Deepest dual with different first and last moves: h#3. The deepest dual overall is h#6, where the two solutions share a first or a last move.
8/8/8/r7/Q7/1kR5/8/1K6 b - - 0 1
Two solutions, with different first and last moves (2 starts, 2 ends).
pure model ideal mirror switchback single-piece single-piece:black zilahi
Note: the diagram has no legal last move, so it cannot arise in a game.