Helpmate tablebases Every solution to every position, precomputed.

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KPvkrb

5 pieces.

h#8.5
longest mate: h#7.5
deepest unique: 6
positions at that depth: h#7.5
deepest dual: h#7
deepest strict dual: 512,317,242
positions with a helpmate: 7,644,033
with a unique solution: 355,074,048
cells in the plane: 271,558,775 bytes
on disk

Deepest unique problems

h#7.5

K7/8/8/8/1r6/b7/P6k/8 w - - 0 1

Ka7 Re4 Kb6 Be7 a4 Kg3 a5 Kf4 a6 Ke5 a7 Kd6 a8=Q Re5 Qc6#

set-play promotion excelsior excelsior:white self-block nocapture nocheck

h#7.5

7k/8/8/8/2b5/8/1P6/1Kr5 w - - 0 1

Kxc1 Kg7 b3 Kf6 b4 Ke5 b5 Kd4 b6 Kc3 b7 Kb3 b8=Q+ Ka2 Qb2#

promotion excelsior excelsior:white closed-walk single-piece single-piece:black

Note: the side to move is in check in the diagram; the solution begins with a capture.

h#7.5

1r6/K7/8/8/2b5/2P5/7k/8 w - - 0 1

Kxb8 Bd5 c4 Kg3 cxd5 Kf4 d6 Ke5 d7 Kd6 Ka7 Kc7 Ka6 Kb8 d8=Q#

pure model ideal mirror promotion switchback kniest nocheck umnov

Note: the solution begins with a capture.

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 one distinct idea exists at this depth: 2 positions share a solution.

h#7

8/8/8/K7/1r1b4/8/P6k/8 b - - 0 1

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

Rb6 a4 Re6 Kb5 Kg3 a5 Kf4 a6 Ke5 a7 Kd6 a8=Q Be5 Qd8#
Rb7 a4 Re7 Kb5 Kg3 a5 Kf4 a6 Ke5 a7 Kd6 a8=Q Be5 Qc6#

pure model ideal promotion excelsior excelsior:white self-block nocapture nocheck