Helpmate tablebases Every solution to every position, precomputed.

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KBvkqqn

6 pieces.

h#12.5
longest mate
h#9.5
deepest unique
341
positions at that depth
h#9.5
deepest dual
h#9
deepest strict dual
3,768,003,377
positions with a helpmate
13,305,249
with a unique solution
7,751,073,792
cells in the plane
2,053,119,633 bytes
on disk

Deepest unique problems

h#9.5

8/1q6/1n6/8/8/8/q7/KBk5 w - - 0 1

  1. Kxa2 Kd2 Be4 Kc3 Bxb7 Kb4 Ba6 Ka5 Kb3 Nc8 Kc4 Kb6 Kd5 Ka7 Kc6 Ka8 Kc7 Na7 Bb7#

pure model ideal switchback self-block nocheck

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

h#9.5

8/8/8/8/6n1/5q2/1q6/K3B1k1 w - - 0 1

  1. Kxb2 Nf6 Bb4 Kf2 Bf8 Ke3 Kc3 Kf4+ Kd4 Kg5 Ke5 Kg6 Ke6 Kh7 Kf7 Kh8 Kg6 Ng8 Bg7#

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/q7/8/k7/2B2n2/qK6 w - - 0 1

  1. Kxa1 Kb4+ Kb1 Kc3 Bd3 Kd2 Bf1 Ke1 Kc2 Nh3 Kd3 Kf2 Ke4 Kg1 Kf3 Kh1 Kg3 Ng1 Bg2#

pure model switchback self-block

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

Only one position exists at this depth.

h#9

8/8/8/4k3/2q5/2Bq4/1n6/K7 b - - 0 1

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

  1. Kf5 Bd2 Qg3 Kb1 Qf1+ Kc2 Nd3 Kc3 Kg4 Kd4 Kh4 Ke4 Nf2+ Kf5 Ng4+ Kg6 Qfh3 Bg5#
  2. Ke6 Bb4 Qc7 Ka2 Qa6+ Kb3 Nc4 Kc3 Kd7 Kd4 Kd8 Kd5 Nb6+ Ke6 Nd7+ Kf7 Qac8 Be7#

pure model ideal self-block nocapture

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