Helpmate tablebases Every solution to every position, precomputed.

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KRvkq

4 pieces.

h#7.5
longest mate: h#5.5
deepest unique: 6
positions at that depth: h#5.5
deepest dual: h#5
deepest strict dual: 2,464,941
positions with a helpmate: 96,106
with a unique solution: 1,892,352
cells in the plane: 1,499,219 bytes
on disk

Deepest unique problems

h#5.5

8/8/5k2/8/8/6R1/5q2/K7 w - - 0 1

Kb1 Qf5+ Kc1 Qg6 Kd2 Kg7 Ke3 Kh6 Kf4 Kh5 Rh3#

pure model ideal self-block nocapture

h#5.5

8/1qR5/6k1/8/8/8/8/K7 w - - 0 1

Ka2 Qd5+ Ka3 Qf7 Kb4 Kg7 Kc5 Kf8 Kd6 Ke8 Rc8#

pure model ideal self-block nocapture

h#5.5

8/3R4/6k1/1q6/8/8/8/K7 w - - 0 1

Ka2 Qe5 Kb3 Qg7 Kc4 Kh7 Kd5 Kg8 Ke6 Kf8 Rd8#

pure model ideal self-block nocapture nocheck

Deepest dual problems

Deepest dual with different first and last moves: h#5. The deepest dual overall is h#5.5, where the two solutions share a first or a last move.

h#5

4k3/3R4/8/8/8/5q2/8/2K5 b - - 0 1

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

Qd1+ Rxd1 Kf7 Kd2 Kg6 Ke3 Kh5 Kf4 Kh4 Rh1#
Qh1+ Rd1 Kf7 Kd2 Kg6 Ke3 Kh5 Kf4 Kh4 Rxh1#

pure model ideal mirror

h#5

4k3/3R4/8/8/1q6/8/8/2K5 b - - 0 1

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

Qe7 Kd2 Kf7 Rxe7+ Kg6 Ke3 Kh5 Kf4 Kh4 Rh7#
Qb5 Rd1 Kf7 Kd2 Kg6 Ke3 Kh5 Kf4 Kh4 Rh1#

pure model ideal mirror

h#5

1q2k3/3R4/8/8/8/8/8/2K5 b - - 0 1

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

Qb5 Rd1 Kf7 Kd2 Kg6 Ke3 Kh5 Kf4 Kh4 Rh1#
Qd8 Rxd8+ Kf7 Kd2 Kg6 Ke3 Kh5 Kf4 Kh4 Rh8#

pure model ideal mirror