Is it mate n 26?

[Uri Blass]

[d]rnbqkb1r/8/8/8/8/8/8/RNBQKBNR w KQkq - 0 1 bm Qxd8+
After some backward analysis

Slow64-avx2 [001]:

27/51 00:03 27,194k 7,451k +M26 Qd1xd8+ Ke8xd8 Rh1xh8 Ra8xa1 Rh8xf8+ Kd8-c7 Bc1-f4+ Kc7-b6 Bf1-d3 Kb6-b7 Bd3-e4+ Nb8-c6 Be4xc6+ Kb7xc6 Rf8xc8+ Kc6-d5 Rc8-b8 Kd5-c6 Ke1-f2 Ra1-a7 Ng1-f3 Ra7-b7 Rb8xb7 Kc6xb7 Nf3-d4 Kb7-c8 Nb1-c3 Kc8-d8 Kf2-f3 Kd8-d7 Kf3-e4 Kd7-e7 Ke4-f5 Ke7-d7 Nc3-d5 Kd7-c8 Kf5-e6 Kc8-b7 Ke6-d7 Kb7-a6 Kd7-c6 Ka6-a5 Bf4-e5 Ka5-a4 Be5-d6 Ka4-a5 Kc6-b7 Ka5-a4 Nd5-c3+ Ka4-a5 Nd4-c6+


13.Nd4 is mate in 14 based on tablebases

[Uri Blass]

It seems to be probably a shorter mate because earlier 10.Ke2 or 10.Kd2 instead of 10.Kf2 is mate in 15
not sure if 9...Kc6 is best (and for exmple 9...Ke6 may lose one move slower)

[Uri Blass]

mate in at most 25 unless black has improvement in one of the first 4 moves.
[d]1nb2R2/8/1k6/8/5B2/3B4/8/rN2K1N1 b - - 4 5
Slow64-avx2 [001]:
34/61 52:45 22,128,087k 6,991k -M20 Bc8-e6 Rf8-f6 Kb6-b7 Rf6xe6 Nb8-a6 Re6xa6 Ra1xa6 Bd3xa6+ Kb7xa6 Nb1-c3 Ka6-a7 Ng1-e2 Ka7-b7 Ne2-d4 Kb7-c8 Ke1-f2 Kc8-d8 Nc3-d5 Kd8-d7 Kf2-e3 Kd7-e8 Ke3-e4 Ke8-f7 Ke4-f5 Kf7-g7 Bf4-e5+ Kg7-f7 Be5-d6 Kf7-g7 Nd4-e6+ Kg7-f7 Nd5-c7 Kf7-g8 Kf5-g6 Kg8-h8 Nc7-d5 Kh8-g8 Nd5-e7+ Kg8-h8 Bd6-e5+
34/61 52:45 22,128,087k 6,991k -M20 Nb8-a6 Rf8xc8 Kb6-b7 Bd3xa6+ Ra1xa6 Rc8-b8+ Kb7-c6 Ng1-e2 Ra6-a7 Ke1-d2 Ra7-b7 Rb8xb7 Kc6xb7 Kd2-e3 Kb7-c6 Ke3-e4 Kc6-b6 Ke4-d5 Kb6-b7 Nb1-c3 Kb7-c8 Kd5-e6 Kc8-b7 Ke6-d6 Kb7-b6 Ne2-d4 Kb6-b7 Nc3-d5 Kb7-c8 Nd4-b5 Kc8-d8 Kd6-c6 Kd8-e8 Nb5-d6+ Ke8-f8 Bf4-h6+ Kf8-g8 Nd5-f6+ Kg8-h8 Nd6-f7+
34/61 52:45 22,128,087k 6,991k -M20 Bc8-b7 Rf8xb8 Ra1-a4 Ng1-e2 Ra4-a8 Rb8xb7+ Kb6xb7 Bd3-e4+ Kb7-a7 Be4xa8 Ka7xa8 Ke1-f2 Ka8-b7 Kf2-f3 Kb7-b6 Ne2-d4 Kb6-b7 Kf3-e4 Kb7-c8 Nb1-c3 Kc8-d7 Ke4-f5 Kd7-c8 Nc3-d5 Kc8-b7 Kf5-e6 Kb7-a7 Ke6-d7 Ka7-a6 Kd7-c6 Ka6-a5 Bf4-c7+ Ka5-a6 Bc7-d8 Ka6-a7 Nd4-b5+ Ka7-b8 Bd8-c7+ Kb8-c8 Nd5-b6+
34/61 52:45 22,128,087k 6,991k -M20 Ra1-a4 Rf8xc8 Ra4xf4 Rc8xb8+ Kb6-c7 Rb8-b5 Rf4-f8 Nb1-c3 Rf8-c8 Ke1-d2 Kc7-d6 Ng1-f3 Rc8-c7 Rb5-b3 Kd6-c5 Kd2-e3 Rc7-e7+ Bd3-e4 Re7-e8 Rb3-b5+ Kc5-d6 Ke3-d4 Re8-d8 Nc3-d5 Kd6-c6 Be4-d3 Kc6-d7 Rb5-b7+ Kd7-c8 Bd3-a6 Rd8-d6 Rb7-b6+ Kc8-d8 Rb6xd6+ Kd8-e8 Nf3-e5 Ke8-f8 Rd6-g6 Kf8-e8 Rg6-g8+
34/61 52:45 22,128,087k 6,991k -M20 Bc8-d7 Rf8xb8+ Kb6-c5 Ke1-d2 Bd7-c6 Nb1-c3 Ra1-a8 Rb8xa8 Bc6xa8 Bd3-e4 Ba8xe4 Nc3xe4+ Kc5-d5 Kd2-e3 Kd5-c4 Bf4-d6 Kc4-d5 Ke3-d3 Kd5-c6 Kd3-c4 Kc6-b7 Ne4-c5+ Kb7-a8 Ng1-f3 Ka8-a7 Kc4-d5 Ka7-b6 Nf3-d4 Kb6-a7 Kd5-c6 Ka7-a8 Bd6-f4 Ka8-a7 Bf4-c7 Ka7-a8 Nc5-a4 Ka8-a7 Nd4-b5+ Ka7-a8 Na4-b6+
---------------------------------------------------------------------------
34/61 56:22 23,677,274k 7,000k -M20 Bc8-e6 Rf8-f6 Kb6-b7 Rf6xe6 Nb8-a6 Re6xa6 Ra1xa6 Bd3xa6+ Kb7xa6 Nb1-c3 Ka6-a7 Ng1-e2 Ka7-b7 Ne2-d4 Kb7-c8 Ke1-f2 Kc8-d8 Nc3-d5 Kd8-d7 Kf2-e3 Kd7-e8 Ke3-e4 Ke8-f7 Ke4-f5 Kf7-g7 Bf4-e5+ Kg7-f7 Be5-d6 Kf7-g7 Nd4-e6+ Kg7-f7 Nd5-c7 Kf7-g8 Kf5-g6 Kg8-h8 Nc7-d5 Kh8-g8 Nd5-e7+ Kg8-h8 Bd6-e5+
34/61 56:22 23,677,274k 7,000k -M20 Nb8-a6 Rf8xc8 Kb6-b7 Bd3xa6+ Ra1xa6 Rc8-b8+ Kb7-c6 Ng1-e2 Ra6-a7 Ke1-d2 Ra7-b7 Rb8xb7 Kc6xb7 Kd2-e3 Kb7-c6 Ke3-e4 Kc6-b6 Ke4-d5 Kb6-b7 Nb1-c3 Kb7-c8 Kd5-e6 Kc8-b7 Ke6-d6 Kb7-b6 Ne2-d4 Kb6-b7 Nc3-d5 Kb7-c8 Nd4-b5 Kc8-d8 Kd6-c6 Kd8-e8 Nb5-d6+ Ke8-f8 Bf4-h6+ Kf8-g8 Nd5-f6+ Kg8-h8 Nd6-f7+
35/61 56:22 23,677,274k 7,000k -M20 Bc8-b7 Rf8xb8 Ra1-a4 Ng1-e2 Ra4-a8 Rb8xb7+ Kb6xb7 Bd3-e4+ Kb7-a7 Be4xa8 Ka7xa8 Ke1-f2 Ka8-b7 Kf2-f3 Kb7-b6 Ne2-d4 Kb6-b7 Kf3-e4 Kb7-c8 Nb1-c3 Kc8-d7 Ke4-f5 Kd7-c8 Nc3-d5 Kc8-b7 Kf5-e6 Kb7-a7 Ke6-d7 Ka7-a6 Kd7-c6 Ka6-a5 Bf4-c7+ Ka5-a6 Bc7-d8 Ka6-a7 Nd4-b5+ Ka7-b8 Bd8-c7+ Kb8-c8 Nd5-b6+
35/61 56:22 23,677,274k 7,000k -M20 Ra1-a4 Rf8xc8 Ra4xf4 Rc8xb8+ Kb6-c7 Rb8-b5 Rf4-f8 Ke1-d2 Rf8-g8 Ng1-e2 Rg8-f8 Nb1-c3 Rf8-f3 Rb5-b1 Rf3-h3 Ne2-f4 Rh3-f3 Bd3-e4 Rf3-g3 Nc3-d5+ Kc7-d7 Rb1-b6 Rg3-g5 Kd2-e3 Rg5-g1 Be4-f5+ Kd7-e8 Rb6-b8+ Ke8-f7 Rb8-b7+ Kf7-e8 Rb7-e7+ Ke8-d8 Nf4-e6+ Kd8-c8 Ne6-d4+ Kc8-b8 Nd4-c6+ Kb8-a8 Re7-a7+
35/61 56:22 23,677,274k 7,000k -M20 Bc8-d7 Rf8xb8+ Kb6-c5 Ke1-d2 Bd7-c6 Nb1-c3 Ra1-a8 Rb8xa8 Bc6xa8 Bd3-e4 Ba8xe4 Nc3xe4+ Kc5-d5 Kd2-e3 Kd5-c4 Bf4-d6 Kc4-d5 Ke3-d3 Kd5-c6 Kd3-c4 Kc6-b7 Ne4-c5+ Kb7-a8 Ng1-f3 Ka8-a7 Kc4-d5 Ka7-b6 Nf3-d4 Kb6-a7 Kd5-c6 Ka7-a8 Bd6-f4 Ka8-a7 Bf4-c7 Ka7-a8 Nc5-a4 Ka8-a7 Nd4-b5+ Ka7-a8 Na4-b6+

[peter]

rnbqkb1r/8/8/8/8/8/8/RNBQKBNR w KQkq - 0 1

Analysis by The Huntsman 1:

1.Dxd8+ Kxd8 2.Txh8 Txa1 3.Txf8+ Kc7 4.Lf4+ Kb6 5.Ld3 Lb7 6.Txb8 Ta8 7.Txb7+ Kxb7 8.Le4+ Ka7 9.Lxa8 Kxa8 10.Se2 Ka7 11.Kf2 Kb7 12.Kf3 Ka7 13.Ke4 Kb7 14.Sd4 Kc8 15.Se6 Kd7 16.Sc5+ Ke7 17.Kf5 Kf7 18.Sc3 Kg7 19.Sd5 Kf7 20.Le5 Kf8 21.Kg6 Ke8 22.Ld6 Kd8 23.Kf7 Kc8 24.Sb6+ Kd8 25.Sb7#
Tiefe: 66/50 00:00:57 2800MN
+- (#25)

After Forward- Backward, regards

[Ajedrecista]

Hello Peter:

rnbqkb1r/8/8/8/8/8/8/RNBQKBNR w KQkq - 0 1

Analysis by The Huntsman 1:

1.Dxd8+ Kxd8 2.Txh8 Txa1 3.Txf8+ Kc7 4.Lf4+ Kb6 5.Ld3 Lb7 6.Txb8 Ta8 7.Txb7+ Kxb7 8.Le4+ Ka7 9.Lxa8 Kxa8 10.Se2 Ka7 11.Kf2 Kb7 12.Kf3 Ka7 13.Ke4 Kb7 14.Sd4 Kc8 15.Se6 Kd7 16.Sc5+ Ke7 17.Kf5 Kf7 18.Sc3 Kg7 19.Sd5 Kf7 20.Le5 Kf8 21.Kg6 Ke8 22.Ld6 Kd8 23.Kf7 Kc8 24.Sb6+ Kd8 25.Sb7#
Tiefe: 66/50 00:00:57 2800MN
+- (#25)

After Forward- Backward, regards

After 12.- Kf3, Shredder online EGTB say that 12.- ..., Ka7 is suboptimal (-#12) instead of king to b6, c6 or c8 (all of them -#13). Again, 14.- Nd4 is suboptimal (+#12) instead of Kd5 (+#11).

Regards from Spain.

Ajedrecista.

[peter]

Hello Peter:

rnbqkb1r/8/8/8/8/8/8/RNBQKBNR w KQkq - 0 1

Analysis by The Huntsman 1:

1.Dxd8+ Kxd8 2.Txh8 Txa1 3.Txf8+ Kc7 4.Lf4+ Kb6 5.Ld3 Lb7 6.Txb8 Ta8 7.Txb7+ Kxb7 8.Le4+ Ka7 9.Lxa8 Kxa8 10.Se2 Ka7 11.Kf2 Kb7 12.Kf3 Ka7 13.Ke4 Kb7 14.Sd4 Kc8 15.Se6 Kd7 16.Sc5+ Ke7 17.Kf5 Kf7 18.Sc3 Kg7 19.Sd5 Kf7 20.Le5 Kf8 21.Kg6 Ke8 22.Ld6 Kd8 23.Kf7 Kc8 24.Sb6+ Kd8 25.Sb7#
Tiefe: 66/50 00:00:57 2800MN
+- (#25)

After Forward- Backward, regards

After 12.- Kf3, Shredder online EGTB say that 12.- ..., Ka7 is suboptimal (-#12) instead of king to b6, c6 or c8 (all of them -#13). Again, 14.- Nd4 is suboptimal (+#12) instead of Kd5 (+#11).

Hi Jesus!
Already after 9.Bxa8 it's #16, here's best line Nalimovs give from there onwards :

rnbqkb1r/8/8/8/8/8/8/RNBQKBNR w KQkq -

1. Qxd8+ Kxd8 2. Rxh8 Rxa1 3. Rxf8+ Kc7 4. Bf4+ Kb6 5. Bd3
Bb7 6. Rxb8 Ra8 7. Rxb7+ Kxb7 8. Be4+ Ka7 9. Bxa8 Kxa8

10. Na3 Ka7 11. Ke2 Kb7 12. Nf3 Kb6 13. Ke3 Kc6 14. Ke4 Kc5
15. Nd4 Kb4 16. Nab5 Kc4 17. Bd2 Kc5 18. Ba5 Kc4 19. Bb6
Kb4 20. Kd3 Ka4 21. Kc2 Kb4 22. Nc3 Kc4 23. Ndb5 Kb4
24. Nd6 Ka3 25. Bc5#

I didn't check output- line of Huntsman's at starting position till very end, that there always can be suboptimal moves from both sides after 10 moves in output doesn't prove DTM wrong as such. Huntsman is very rarely wrong giving too short lines, too long ones occure much more often just because of lack of hardware- time, regards