Helpmate tablebases Every solution to every position, precomputed.

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KBvkqbb

6 pieces.

h#10.5
longest mate
h#8.5
deepest unique
25
positions at that depth
h#8.5
deepest dual
h#7
deepest strict dual
3,118,953,592
positions with a helpmate
39,815,016
with a unique solution
7,751,073,792
cells in the plane
2,704,368,203 bytes
on disk

Deepest unique problems

h#8.5

5b2/8/8/8/7B/7b/7k/Kq6 w - - 0 1

  1. Kxb1 Bf5+ Kb2 Kh3 Kc3 Kg4 Kd4 Kh5 Ke5 Kh6 Kf6 Kh7 Kf7 Kh8 Kxf8 Bh7 Bf6#

self-block

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

h#8.5

1kbB4/8/7b/8/8/8/q7/1K6 w - - 0 1

  1. Kxa2 Be6+ Kb2 Kc8 Kc3 Kd7 Kd4 Ke8 Ke5 Kf8 Kf6 Kg8 Kg6 Kh8 Kxh6 Bg8 Bf6#

self-block

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

h#8.5

b7/8/8/8/8/8/2B2b2/k1Kq4 w - - 0 1

  1. Kxd1 Kb2 Be4 Kc3 Bxa8 Kd3 Kc1 Ke2 Kc2 Kf1 Kd3 Kg1 Ke4 Kh1 Kf3 Bg1 Kg3#

switchback self-block nocheck

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#7. The deepest dual overall is h#8.5, where the two solutions share a first or a last move.

Only one position exists at this depth.

h#7

8/8/6k1/1q5B/b7/8/8/K1b5 b - - 0 1

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

  1. Kg5 Bd1 Qa6 Kb1 Be8 Kc2 Qh6 Kd3 Bg6+ Ke2 Kh5 Kf3 Bg5 Kg3#
  2. Kh6 Be8 Bb3 Kb1 Bf7+ Kc2 Qg5 Kd3 Kh5 Ke4 Qh4+ Kf5 Bh6 Bxf7#

self-block

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