Helpmate tablebases Every solution to every position, precomputed.

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KBvkrn

5 pieces.

h#12.5
longest mate: h#9.5
deepest unique: 24
positions at that depth: h#10
deepest dual: h#7.5
deepest strict dual: 163,904,715
positions with a helpmate: 315,549
with a unique solution: 121,110,528
cells in the plane: 49,829,726 bytes
on disk

Deepest unique problems

h#9.5

8/8/5r2/8/8/1k6/4B3/1K1n4 w - - 0 1

Kc1 Nf2 Kd2 Nh3 Ke3 Kc2 Bd3+ Kd1 Bf5 Ke1 Kf3 Kf1 Kg3 Kg1 Bd3 Kh1 Bf1 Ng1 Bg2#

pure model switchback self-block nocapture

h#9.5

8/2r5/8/8/4n3/8/k7/2KB4 w - - 0 1

Bc2 Nd6 Kd2 Ka3 Bd3 Kb4 Ba6 Kc5 Kc3 Kb6+ Kb4 Ka7 Ka5 Ka8 Kb6 Nc8+ Kxc7 Na7 Bb7#

pure model ideal self-block

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

h#9.5

8/8/8/8/2rB4/1n6/7k/2K5 w - - 0 1

Kd1 Kg3 Ke2 Kf4 Kd3 Nc1+ Kxc4 Ke4 Kb4 Kd3 Bb2 Kc2 Ba3 Kb1 Kc3 Ka1 Kc2 Na2 Bb2#

pure model ideal switchback self-block

Note: the diagram has no legal last move, so it cannot arise in a game.

Deepest dual problems

Deepest dual with different first and last moves: h#7.5. The deepest dual overall is h#10, where the two solutions share a first or a last move.

Only one distinct idea exists at this depth: 3 positions share a solution.

h#7.5

8/4kn2/8/8/8/8/6r1/1K4B1 w - - 0 1

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

Bd4 Rg1+ Kc2 Kf8 Kd3 Kg8 Ke4 Ng5+ Ke5 Kh8 Kf6 Nh7+ Kf7+ Rg7+ Bxg7#
Bc5+ Kf6 Bf8 Rc2 Kxc2 Kg6 Kd3 Kh7 Ke4 Kh8 Kf5 Nh6+ Kg6 Ng8 Bg7#

pure model ideal self-block umnov