Helpmate tablebases Every solution to every position, precomputed.

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KBvkqrb

6 pieces.

h#8.5
longest mate
h#7.5
deepest unique
2
positions at that depth
h#7.5
deepest dual
h#6.5
deepest strict dual
4,016,753,103
positions with a helpmate
48,950,075
with a unique solution
7,751,073,792
cells in the plane
3,344,811,204 bytes
on disk

Deepest unique problems

Only 2 distinct ideas exist at this depth.

h#7.5

8/7k/7b/8/8/8/B2r4/K1q5 w - - 0 1

  1. Bb1+ Qc2 Ba2 Qb1+ Kxb1 Rd1+ Kc2 Rh1 Kd3 Kg6 Ke4 Kh5 Kf5 Rh4 Bf7#

switchback self-block umnov

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

h#7.5

8/7k/8/8/8/b7/Br6/K2q4 w - - 0 1

  1. Bb1+ Qd3 Bc2 Be7 Kxb2 Qg6 Kc3 Kh6 Kd4 Kh5 Ke5 Qh6 Kf5 Bh4 Bd1#

self-block

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

Deepest dual problems

Deepest dual with different first and last moves: h#6.5. The deepest dual overall is h#7.5, where the two solutions share a first or a last move.

h#6.5

8/8/8/1r6/8/8/b2q1B2/K6k w - - 0 1

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

  1. Be3 Bb3 Kb1 Qg2 Kc1 Be6 Kd1 Kh2 Ke1 Qh1+ Kf2 Bh3 Bf4#
  2. Bh4 Bb3 Kb1 Qg2 Kc1 Be6 Kd1 Kh2 Ke1 Qh1+ Kf2 Bh3 Bg3#

pure model self-block nocapture

h#6.5

8/8/4b2B/8/8/1r6/2q3k1/K7 w - - 0 1

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

  1. Bg7 Qc1+ Ka2 Bg4 Kxb3 Qf1 Kc3 Kf2 Kd4 Ke1 Ke3 Bd1 Bc3#
  2. Bf8 Qc1+ Ka2 Bg4 Kxb3 Qf1 Kc3 Kf2 Kd4 Ke1 Ke3 Bd1 Bb4#

self-block

h#6.5

2r5/b7/8/8/3k4/8/3q4/KB6 w - - 0 1

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

  1. Be4 Kc3 Bc6 Kc2 Ka2 Kd1+ Kb3 Bf2 Kc4 Qc1+ Kd3 Be1 Bf3#
  2. Bf5 Kc3 Bxc8 Kc2 Ka2 Kd1+ Kb3 Bf2 Kc4 Qc1+ Kd3 Be1 Bg4#

self-block