h#4
8/8/8/8/8/8/1R6/K4kR1 b - - 0 1
- Kxg1 Kb1 Kf1 Kc2 Ke1 Kd3 Kd1 Rb1#
pure model ideal mirror switchback single-piece single-piece:black nocheck
Note: the side to move is in check in the diagram; the solution begins with a capture.
KRRvk
4 pieces.
- h#7
- longest mate
- h#4
- deepest unique
- 27
- positions at that depth
- h#5
- deepest dual
- h#3
- deepest strict dual
- 1,372,472
- positions with a helpmate
- 176,868
- with a unique solution
- 1,892,352
- cells in the plane
- 847,686 bytes
- on disk
Deepest unique problems
h#4
8/8/8/8/8/8/2R5/1K4kR b - - 0 1
- Kxh1 Kc1 Kg1 Kd2 Kf1 Ke3 Ke1 Rc1#
pure model ideal mirror switchback single-piece single-piece:black nocheck
Note: the side to move is in check in the diagram; the solution begins with a capture.
h#4
8/7R/7k/8/8/8/8/2K3R1 b - - 0 1
- Kxh7 Kd2 Kh6 Ke3 Kh5 Kf4 Kh4 Rh1#
pure model ideal mirror switchback single-piece single-piece:black nocheck
Note: the side to move is in check in the diagram; the solution begins with a capture.
Deepest dual problems
Deepest dual with different first and last moves: h#3. The deepest dual overall is h#5, where the two solutions share a first or a last move.
Only 2 distinct ideas exist at this depth.
h#3
8/8/8/8/1k6/8/8/RKR5 b - - 0 1
Two solutions, with different first and last moves (2 starts, 2 ends).
- Kb3 Rd1 Kc3 Ka2 Kc2 Rac1#
- Kb5 Kc2 Kb4 Kd3 Kb3 Rcb1#
set-play pure model ideal mirror switchback single-piece single-piece:black nocapture nocheck
h#3
8/8/8/8/8/8/6R1/3K1Rk1 b - - 0 1
Two solutions, with different first and last moves (2 starts, 2 ends).
- Kxf1 Kc2 Ke1 Kd3 Kd1 Rg1#
- Kxg2 Ke2 Kh2 Kf3 Kh3 Rh1#
pure model ideal mirror single-piece single-piece:black nocheck zilahi
Note: the diagram has no legal last move, so it cannot arise in a game.