h#7.5
7b/8/8/4k3/8/8/B1q3q1/1K6 w - - 0 1
- Ka1 Kd4 Bd5 Kc3 Bxg2 Qc1+ Ka2 Kd2 Kb3 Bc3 Kc4 Kd1 Kd3 Be1 Bf3#
Note: the side to move is in check in the diagram.
KBvkqqb
6 pieces.
- h#8.5
- longest mate
- h#7.5
- deepest unique
- 8
- positions at that depth
- h#7.5
- deepest dual
- h#7
- deepest strict dual
- 1,848,105,798
- positions with a helpmate
- 22,104,926
- with a unique solution
- 7,751,073,792
- cells in the plane
- 1,799,825,839 bytes
- on disk
Deepest unique problems
h#7.5
7k/8/6B1/1q6/8/1q6/1K6/2b5 w - - 0 1
- Ka1 Qg5 Bh7 Qb1+ Kxb1 Kg7 Kc2 Kh6 Kd3 Kh5 Ke4 Qh4+ Kf5 Bh6 Bg6#
pure model ideal switchback self-block
Note: the diagram has no legal last move, so it cannot arise in a game.
h#7.5
7k/5B2/8/8/8/b7/2q1q3/1K6 w - - 0 1
- Ka1 Qe7 Bg8 Qa2+ Kxa2 Kg7 Kb3 Kf8 Kc4 Ke8 Kd5 Qd8+ Ke6 Bf8 Bf7#
pure model ideal switchback self-block
Note: the side to move is in check in the diagram.
Deepest dual problems
Deepest dual with different first and last moves: h#7. The deepest dual overall is h#7.5, where the two solutions share a first or a last move.
Only 2 distinct ideas exist at this depth.
h#7
7k/8/8/8/8/1q6/2qb4/K4B2 b - - 0 1
Two solutions, with different first and last moves (2 starts, 2 ends).
- Qh7 Bd3 Qbg8 Kb2 Bh6 Kc3 Kg7 Kd4 Qhh8 Ke4 Kh7 Kf5 Bg7 Kg5#
- Qg8 Bc4 Qch7 Kb2 Bh6 Kc3 Kg7 Kd4 Qgh8 Kd5 Kg8 Ke6 Bg7 Ke7#
h#7
7k/8/8/8/8/1q6/2q1B2b/K7 b - - 0 1
Two solutions, with different first and last moves (2 starts, 2 ends).
- Qh7 Bd3 Qbg8 Kb2 Kg7 Kc3 Qhh8 Kd4 Be5+ Ke4 Kh7 Kf5 Bg7 Kg5#
- Qg8 Bc4 Qch7 Kb2 Kg7 Kc3 Qgh8 Kd4 Be5+ Kd5 Kg8 Ke6 Bg7 Ke7#