Helpmate tablebases Every solution to every position, precomputed.

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KQNvkp

5 pieces.

h#11
longest mate: h#8
deepest unique: 2
positions at that depth: h#8
deepest dual: h#3.5
deepest strict dual: 487,771,654
positions with a helpmate: 50,263,728
with a unique solution: 355,074,048
cells in the plane: 354,089,024 bytes
on disk

Deepest unique problems

Only 2 distinct ideas exist at this depth.

h#8

8/8/8/3p4/8/kQ6/N7/K7 b - - 0 1

Kxb3 Kb1 d4 Kc1 d3 Kd2 Kb2 Nb4 Ka1 Kc3 d2 Kb3 d1=R Ka3 Rb1 Nc2#

pure model ideal promotion underpromotion self-block nocheck umnov

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

h#8

8/8/8/4p3/8/kQ6/N7/K7 b - - 0 1

Kxb3 Kb1 e4 Kc1 e3 Kd1 Kb2 Nb4 Ka1 Kc2 e2 Kb3 e1=R Ka3 Rb1 Nc2#

pure model ideal promotion underpromotion 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#3.5. The deepest dual overall is h#8, where the two solutions share a first or a last move.

h#3.5

8/8/1N5k/8/8/8/1p6/K4Q2 w - - 0 1

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

Ka2 b1=R Nd7 Rb5 Nf8 Rh5 Qf6#
Kxb2 Kg5 Qg2+ Kf4 Kc3 Ke3 Nd5#

mirror promotion underpromotion self-block single-piece single-piece:black

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

h#3.5

k7/8/8/8/p7/4Q3/8/K6N w - - 0 1

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

Kb2 Kb7 Kc3 Ka6 Kc4 Ka5 Qa7#
Nf2 Kb7 Nd3 Ka6 Nb4+ Ka5 Qc5#

pure model single-piece single-piece:black nocapture

h#3.5

1k6/8/8/8/8/6p1/2Q5/K6N w - - 0 1

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

Nf2 g2 Ne4 g1=B Nd6 Ba7 Qc8#
Qh7 Kc8 Nxg3 Kd8 Nf5 Ke8 Qe7#

pure model promotion underpromotion self-block single-piece single-piece:black nocheck