Helpmate tablebases Every solution to every position, precomputed.

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KBPvk

4 pieces.

h#8
longest mate: h#7
deepest unique: 12
positions at that depth: h#7
deepest dual: h#6.5
deepest strict dual: 9,436,261
positions with a helpmate: 285,389
with a unique solution: 5,548,032
cells in the plane: 7,581,996 bytes
on disk

Deepest unique problems

h#7

7k/8/8/8/B7/8/P7/3K4 b - - 0 1

Kg7 Bb3 Kf6 a4 Ke5 a5 Kd4 a6 Kc3 a7 Kb2 a8=Q Kb1 Qa2#

promotion excelsior excelsior:white closed-walk single-piece single-piece:black nocapture nocheck

Published as Elkies (2004)

Elkies, Noam D. — The Problemist, No. H2794, 07/2004

h#7

8/8/8/8/8/2BK3k/3P4/8 b - - 0 1

Kg4 Kc2 Kf5 d4 Ke6 d5+ Kd7 d6 Kc6 d7 Kb5 d8=Q Ka4 Qa5#

promotion excelsior excelsior:white single-piece single-piece:black nocapture umnov

h#7

8/8/8/K7/7B/8/7P/6k1 b - - 0 1

Kg2 Bg3 Kf3 h4 Ke4 h5 Kd5 h6 Kc6 h7 Kb7 h8=Q Ka7 Qb8#

promotion excelsior excelsior:white single-piece single-piece:black nocapture nocheck

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.

Only one position exists at this depth.

h#6.5

5B1k/8/8/8/8/2K5/2P5/8 w - - 0 1

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

Kd2 Kg8 c4 Kf7 c5 Ke6 c6 Kd5 c7 Kc4 c8=Q+ Kb3 Qc2#
Kb4 Kg8 c4 Kf7 c5 Ke6 c6 Kd5 c7 Kc6 c8=Q+ Kb6 Bc5#

pure model ideal promotion excelsior excelsior:white closed-walk single-piece single-piece:black nocapture umnov