Helpmate tablebases Every solution to every position, precomputed.

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KPvkr

4 pieces.

h#8.5
longest mate
h#7.5
deepest unique
1
positions at that depth
h#7
deepest dual
h#6.5
deepest strict dual
9,026,202
positions with a helpmate
111,229
with a unique solution
5,548,032
cells in the plane
4,725,015 bytes
on disk

Deepest unique problems

Only one position exists at this depth.

Deepest dual problems

Deepest dual with different first and last moves: h#6.5. The deepest dual overall is h#7, where the two solutions share a first or a last move.

h#6.5

8/8/6k1/8/6r1/6P1/1K6/8 w - - 0 1

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

  1. Ka3 Rh4 gxh4 Kf5 h5 Ke4 h6 Kd3 h7 Kc2 h8=Q Kb1 Qb2#
  2. Kc3 Rf4 gxf4 Kh5 f5 Kg4 f6 Kf3 f7 Ke2 f8=Q Kd1 Qf1#

pure model ideal mirror promotion nocheck

h#6.5

8/5k2/8/8/3r4/3P4/1K6/8 w - - 0 1

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

  1. Kc1 Re4 dxe4 Ke6 e5 Kd5 e6 Kc4 e7 Kb3 e8=Q Ka2 Qa4#
  2. Kc3 Rc4+ dxc4 Ke6 c5 Kd5 c6 Kc5 c7 Kb5 c8=Q Ka4 Qa6#

pure model ideal mirror promotion umnov

h#6.5

8/8/6k1/8/4r3/1K2P3/8/8 w - - 0 1

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

  1. Ka3 Rd4 exd4 Kf5 d5 Ke4 d6 Kd3 d7 Kc2 d8=Q Kb1 Qd1#
  2. Kc3 Rf4 exf4 Kh5 f5 Kg4 f6 Kf3 f7 Ke2 f8=Q Kd1 Qf1#

set-play pure model ideal mirror promotion nocheck