h#8.5
8/7k/N7/8/8/8/4r3/Kr6 w - - 0 1
- Kxb1 Kg6 Nb4 Kf5 Nc2 Ke4 Kb2 Kd3 Kc1 Kc3 Kd1 Kb2 Nd4 Ka1 Kc1 Ra2 Nb3#
pure model ideal switchback self-block nocheck
Note: the side to move is in check in the diagram; the solution begins with a capture.
5 pieces.
8/7k/N7/8/8/8/4r3/Kr6 w - - 0 1
pure model ideal switchback self-block nocheck
Note: the side to move is in check in the diagram; the solution begins with a capture.
8/8/8/8/8/7k/5r1N/rK6 w - - 0 1
pure model ideal switchback self-block kniest
Note: the side to move is in check in the diagram; the solution begins with a capture.
8/7k/N7/8/8/8/5r2/1rK5 w - - 0 1
pure model ideal switchback closed-walk self-block nocheck
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#6.5. The deepest dual overall is h#8.5, where the two solutions share a first or a last move.