KBBvk

h#6.5

7k/8/7B/8/8/8/2B5/K7 w - - 0 1

1. Kb2 Kg8 Kc3 Kf7 Kd3 Kg6 Ke4 Kh5 Kf5 Kh4 Bg5+ Kh5 Bd1#

switchback single-piece single-piece:black nocapture

h#4

8/8/7k/8/8/8/3KB2B/8 b - - 0 1

Two solutions, with different first and last moves (2 starts, 2 ends).

1. Kg5 Ke3 Kh4 Kf4 Kh3 Bg4+ Kh4 Bg3#
2. Kg6 Ke3 Kg5 Kf3 Kh4 Bg3+ Kh3 Bf1#

set-play pure model ideal switchback single-piece single-piece:black nocapture

h#4

8/8/8/5k2/8/3KB2B/8/8 b - - 0 1

Two solutions, with different first and last moves (2 starts, 2 ends).

1. Kf6 Ke4 Kg6 Kf4 Kh5 Bg4+ Kh4 Bf2#
2. Kg6 Ke4 Kh5 Kf5 Kh4 Bg5+ Kh5 Bg4#

pure model ideal switchback single-piece single-piece:black nocapture

Note: the side to move is in check in the diagram.

h#4

5k2/1B6/5B2/8/8/3K4/8/8 b - - 0 1

Two solutions, with different first and last moves (2 starts, 2 ends).

1. Ke8 Kc4 Kd7 Kb5 Kc7 Ka6 Kb8 Be5#
2. Kg8 Ke4 Kh7 Kf5 Kh6 Bg5+ Kh5 Bf3#

pure model ideal single-piece single-piece:black nocapture