Helpmate tablebases Every solution to every position, precomputed.

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KNvknn

5 pieces.

h#9.5
longest mate
h#8.5
deepest unique
3
positions at that depth
h#8
deepest dual
h#6.5
deepest strict dual
90,133,257
positions with a helpmate
330,919
with a unique solution
121,110,528
cells in the plane
49,470,692 bytes
on disk

Deepest unique problems

h#8.5

7k/8/8/n7/8/n7/N7/1K6 w - - 0 1

  1. Kb2 Kg7 Kc3 Kf6 Kb4 Ke5 Ka4 Kd4 Nb4 Kc3 Kxa5 Kb2 Ka4 Ka1 Kb3 Nb1 Nc2#

pure model ideal switchback self-block nocheck

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#8, where the two solutions share a first or a last move.

h#6.5

8/8/6nn/8/8/2kN4/8/K7 w - - 0 1

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

  1. Kb1 Nf4 Kc1 Ne2+ Kd1 Nc1 Nc5 Kb2 Kd2 Ka1 Kc2 Na2 Nb3#
  2. Ka2 Ne5 Ka3 Nc4+ Ka4 Na3 Ne1 Kb2 Kb4 Ka1 Kb3 Nb1 Nc2#

pure model self-block nocapture umnov

h#6.5

8/8/8/4k3/2nn4/8/8/1KN5 w - - 0 1

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

  1. Ne2 Ke4 Kc1 Kf3 Kd1 Kg2 Ke1 Kh1 Kf1 Nf3 Kf2 Nh2 Ng3#
  2. Nd3+ Ke4 Kc1 Kf3 Kd1 Kg2 Ke1 Kh1 Kf2 Nf3 Kg3 Ng1 Nf2#

set-play pure model self-block nocapture

h#6.5

6N1/5k2/8/8/8/4n3/4n3/1K6 w - - 0 1

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

  1. Kb2 Nf4 Kc3 Ke8 Kd4 Ne6+ Ke5 Nd8 Kf6 Nd5+ Kg7 Ne7 Nf6#
  2. Ne7 Ng4 Kc2 Kf6 Kd3 Kg5 Ke4 Kh4 Kf5 Ng1 Kg6 Nh3 Nf5#

pure model ideal self-block nocapture