Helpmate tablebases Every solution to every position, precomputed.

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KQvkq

4 pieces.

h#7
longest mate
h#5.5
deepest unique
7
positions at that depth
h#5.5
deepest dual
h#4.5
deepest strict dual
2,224,699
positions with a helpmate
102,226
with a unique solution
1,892,352
cells in the plane
1,808,839 bytes
on disk

Deepest unique problems

h#5.5

8/8/5k2/8/6Q1/q7/8/K7 w - - 0 1

  1. Kb1 Qd3+ Kc1 Qg6 Kd2 Kg7 Ke3 Kh6 Kf4 Qh7 Qg5#

pure model ideal self-block nocapture

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

Published as Sheglow (1998)

  • Sheglow, Wiktor S. — Suomen Tehtäväniekat, No. (257), 05-06/1998

Deepest dual problems

Deepest dual with different first and last moves: h#4.5. The deepest dual overall is h#5.5, where the two solutions share a first or a last move.

h#4.5

1Q6/8/8/8/7k/8/2q5/K7 w - - 0 1

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

  1. Qb2 Qb1+ Kxb1 Kg3 Kc2 Kf2 Kd3+ Ke1 Qe2#
  2. Qe8 Qg2 Kb1 Kg3 Kc1 Kf2 Kd1 Kf1 Qe1#

self-block

h#4.5

4k3/8/8/6q1/8/8/8/2KQ4 w - - 0 1

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

  1. Kc2 Kf7 Kd3 Kg6 Ke2 Kh5 Kf3 Kh4 Qh1#
  2. Qd2 Kf7 Kd1 Kg6 Ke2 Kh5 Kf3 Kh4 Qh2#

pure model ideal single-piece single-piece:black nocapture nocheck

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

h#4.5

4k3/1q5Q/8/8/8/8/8/2K5 w - - 0 1

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

  1. Kd2 Kf8 Qf5+ Kg7 Ke3 Kh6 Kf4 Qh7 Qg5#
  2. Qh8+ Kf7 Kd2 Kg6 Ke3 Qh7 Kf4 Kh5 Qxh7#

pure model ideal mirror switchback self-block