Helpmate tablebases Every solution to every position, precomputed.

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KBvkqbn

6 pieces.

h#12.5
longest mate
h#9.5
deepest unique
90
positions at that depth
h#9.5
deepest dual
h#8
deepest strict dual
8,494,337,674
positions with a helpmate
61,652,763
with a unique solution
7,751,073,792
cells in the plane
4,156,844,486 bytes
on disk

Deepest unique problems

h#9.5

7n/8/2B5/3b4/8/2k5/2q5/1K6 w - - 0 1

  1. Ka1 Kb4 Bb5 Qc5 Kb2 Bb3 Bc4 Ka4 Kc3 Qa3 Kd4 Ng6 Kd5 Nf4+ Kc6 Nd3 Kb6 Nb4 Bb5#

pure model ideal switchback self-block nocapture

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

h#9.5

8/8/8/8/n7/2q5/b1k5/K4B2 w - - 0 1

  1. Kxa2 Nc5 Bc4 Na6 Bb3+ Kd3 Ka3 Kd4 Ka4 Kc5 Be6 Kb6 Bc8 Ka7 Kb5 Ka8 Kb6 Nb8 Bb7#

pure model self-block

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

h#9.5

8/8/8/8/8/k7/2B2n2/1Kq4b w - - 0 1

  1. Kxc1 Nh3 Kd2 Kb2 Ke3 Kc1 Be4 Kd1 Bxh1 Ke1 Kf3 Kf1 Bg2+ Kg1 Bf1 Kh1 Kg3 Ng1 Bg2#

pure model ideal switchback self-block kniest umnov

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#8. The deepest dual overall is h#9.5, where the two solutions share a first or a last move.

h#8

8/8/6k1/3q4/8/8/n1B5/K6b b - - 0 1

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

  1. Kh5 Kb2 Qg5 Kb3 Nc3 Kc4 Ne4 Kd4 Qh4 Ke5 Ng5 Kf6 Bf3 Kg7 Bg4 Bg6#
  2. Kf7 Kb2 Nb4 Kc3 Qd8 Bb3+ Nd5+ Kd4 Ke8 Ke5 Ne7 Kf6 Bc6 Kg7 Bd7 Bf7#

pure model ideal self-block nocapture

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

h#8

7b/8/5k2/8/8/2q5/1B6/nK6 b - - 0 1

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

  1. Nc2 Bc1 Qh3 Kb2 Ne3 Kc3 Kg5+ Kd3 Kh4 Ke4 Ng4 Kf5 Be5 Kg6 Bg3 Bg5#
  2. Nb3 Ba3 Qc8 Kb2 Nc5 Kc3 Ke7+ Kc4 Kd8 Kd5 Nd7 Ke6 Be5 Kf7 Bc7 Be7#

pure model ideal self-block nocapture

h#8

8/8/B3k3/8/3qb3/8/8/1nK5 b - - 0 1

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

  1. Bc6 Kc2 Qd8 Bc4+ Kd7 Kd3 Nc3 Kd4 Nd5 Ke5 Ne7 Kf6 Ke8 Kg7 Bd7 Bf7#
  2. Qd8 Kb2 Na3 Kc3 Kd7 Kd4 Nb5+ Ke5 Qb8+ Kf6 Nc7 Bb5+ Kc8 Ke7 Bb7 Bd7#

pure model ideal self-block nocapture umnov