Mate in 8 - hard for some easy for others

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JVMerlino
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Joined: Wed Mar 08, 2006 10:15 pm
Location: San Francisco, California

Re: Mate in 8 - hard for some easy for others

Post by JVMerlino »

The King from Chessmaster 9000 is a classic at mate finding. It announced Mate in 8 in about 0.15 seconds:

Code: Select all

Time	Depth	Score	Positions	Moves
0:00	1/3	2.83	670		1.Ne6 c5 2.Nxc5 Kc7 3.Nb5+ Kc6
					4.Kb4
0:00	1/4	2.70	2059		1.Ne6 c5 2.Nxc5 Kc7 3.Nb5+ Kc6
					4.Nd3 Kd5
0:00	1/5	2.95	4582		1.Ne6 c5 2.Nxc5 Kc7 3.Nb5+ Kc6
					4.Nd3 Kd7 5.Kb4
0:00	2/6	2.97	10721		1.Ne6 c5 2.Nxc5 Kc7 3.Nb5+ Kd8
					4.Kb4 Ke7 5.Kc4
0:00	3/7	3.12	30692		1.Ne6 c5 2.Nxc5 Kc7 3.Nb5+ Kc8
					4.c4 Kd8 5.Kb4 Ke7
0:00	4/8	7.83	73714		1.Ne6 c5 2.Kb5 c4 3.Nxc4 Kc8 4.Kc6
					Kb8 5.Nc7 Kc8 6.Nxa8 Kb8 7.Nc7
0:00	5/9	7.82	168799		1.Ne6 c5 2.Kb5 c4 3.Nxc4 Kc8 4.Kc6
					Kb8 5.Nc7 Kc8 6.Nxa8 Kd8 7.Nd6 Ke7
0:00	6/10	Mate08	411293		1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nf5
					Kc8 5.Kd6 Kb8 6.Ned4 Kc8 7.Nc6
					Rb8 8.Nfe7#
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kiroje
Posts: 78
Joined: Wed Jul 25, 2012 10:12 am
Location: Copenhagen, Denmark
Full name: Kim Jensen

Re: Mate in 8 - hard for some easy for others

Post by kiroje »

JVMerlino wrote: ↑Tue May 19, 2026 2:01 am The King from Chessmaster 9000 is a classic at mate finding. It announced Mate in 8 in about 0.15 seconds:

Code: Select all

Time	Depth	Score	Positions	Moves
0:00	1/3	2.83	670		1.Ne6 c5 2.Nxc5 Kc7 3.Nb5+ Kc6
					4.Kb4
0:00	1/4	2.70	2059		1.Ne6 c5 2.Nxc5 Kc7 3.Nb5+ Kc6
					4.Nd3 Kd5
0:00	1/5	2.95	4582		1.Ne6 c5 2.Nxc5 Kc7 3.Nb5+ Kc6
					4.Nd3 Kd7 5.Kb4
0:00	2/6	2.97	10721		1.Ne6 c5 2.Nxc5 Kc7 3.Nb5+ Kd8
					4.Kb4 Ke7 5.Kc4
0:00	3/7	3.12	30692		1.Ne6 c5 2.Nxc5 Kc7 3.Nb5+ Kc8
					4.c4 Kd8 5.Kb4 Ke7
0:00	4/8	7.83	73714		1.Ne6 c5 2.Kb5 c4 3.Nxc4 Kc8 4.Kc6
					Kb8 5.Nc7 Kc8 6.Nxa8 Kb8 7.Nc7
0:00	5/9	7.82	168799		1.Ne6 c5 2.Kb5 c4 3.Nxc4 Kc8 4.Kc6
					Kb8 5.Nc7 Kc8 6.Nxa8 Kd8 7.Nd6 Ke7
0:00	6/10	Mate08	411293		1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nf5
					Kc8 5.Kd6 Kb8 6.Ned4 Kc8 7.Nc6
					Rb8 8.Nfe7#
I have always been impressed by de Konig's program - it is amazingly good
“Modern chess is too much concerned with things like pawn structure. Forget it, checkmate ends the game.” – Nigel Short
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kiroje
Posts: 78
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Location: Copenhagen, Denmark
Full name: Kim Jensen

Re: Mate in 8 - hard for some easy for others

Post by kiroje »

Aleks Peshkov wrote: ↑Tue May 19, 2026 12:31 am

Code: Select all

info depth 24 nodes 35942 time 11 nps 2489609 score cp 1103 pv c5e6 c6c5 a5b5 c5c4 d6c4 b8c8 b5c6 c8b8 c4e5 b8c8 e5d7 a8b8 d7b8 c8b8 c2c4 b8a8 c4c5 a8b8 e6c7 b8c8 c7d5 c8b8 d5b4 b8a8
info depth 24 nodes 1199321 time 510 nps 2331449 score mate 8 pv c5e6 c6c5 a5b5 c5c4 b5c6 c4c3 d6b5 b8c8 c6d6 c8b8 e6d8 b8c8 d8c6 a8b8 b5a7
petrel dev. Remarkable unexpected search explosion.
ahh yes - it solves it though :)
I think the problem could be that white can win the rook and then it can mate black it just takes much longer.
“Modern chess is too much concerned with things like pawn structure. Forget it, checkmate ends the game.” – Nigel Short
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towforce
Posts: 13070
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Location: Birmingham UK
Full name: Graham Laight

Re: Mate in 8 - hard for some easy for others

Post by towforce »

kiroje wrote: ↑Mon May 18, 2026 2:06 pmStockfish 18 - 1 thread 8GB hash

Code: Select all

6:55/157-16: 1.Ne6, 507,6M nodes (1,2M nps), 8GB hash
0:00: +2.37/1 1.Ne6
0:00: +3.25/2 1.Ne6
0:00: +3.14/3 1.Ne6 c5 2.c3
0:00: +3.34/4 1.Ne6 c5 2.c3 c4
0:00: +3.27/5 1.Ne6 c5 2.Kb5 c4 3.c3
0:00: +3.01/6 1.Ne6 c5 2.Kb5 c4 3.Ka4 c3
0:00: +2.81/7 1.Ne6 c5 2.Kb5 c4 3.Kb4
0:00: +3.41/8 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8
0:00: +3.43/9 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7
0:00: +3.64/10 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8
0:00: +3.48/11 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Rc8 8.a7
0:00: +3.95/12 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Rc8 8.a7 Ke7 9.Kb6
0:00: +4.23/13 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Rc8 8.a7 Ke7 9.Kb6 Rg8 10.Nd5+ Ke6
0:00: +4.51/14 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Rc8 8.a7 Ke7 9.Kb6 Kf6 10.Nd4 Rg8 11.Nd5+ Ke5
0:00: +4.70/15 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.a7 Rc8 9.Nxc3 Kf6 10.Kb7 Rh8 11.N3d5+ Ke5 12.Nb6 Kd4
0:00: +5.15/16 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rg8
0:00: +5.91/17 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.a7 Rf8
0:02: +6.67/18 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rb2 9.a7 Kf8
0:04: +7.74/19 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Kf6 9.a7 Rc8 10.Kb7 Rg8 11.N3b5 Rg5
0:09: +8.23/20 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.Nd5+ Kf7 10.a7 Kg6
0:15: +9.06/21 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.Nd5+ Kf7 10.a7 Kg8
0:46: +11.36/22 1.Ne6
0:57: +11.36/22 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.Nd5+ Kf7 10.a7 Kg7 11.Kb7
1:11: +14.41/23 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.Nd5+ Kf7 10.a7 Kg7 11.Kb7 Kh7
1:30: +19.46/24 1.Ne6
1:51: +26.41/24 1.Ne6
1:55: +17.14/24 1.Ne6 c5
1:55: +17.14/24 1.Ne6
2:09: +34.61/24 1.Ne6
2:26: +56.59/24 1.Ne6
2:26: +27.29/24 1.Ne6 c5
2:26: +27.29/24 1.Ne6
2:38: +68.43/24 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.Nd5+ Kf8 10.a7 Kg7 11.Kb7 Rh8 12.c4 Kf7 13.c5
6:21: #26/25 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.a7 Rg8 10.a8=Q Rg6+ 11.Kb7 Kf6 12.Qa6+ Kg5 13.Qxg6+ Kxg6 14.N3b5 Kh6 15.c4 Kg6 16.c5 Kg5 17.c6 Kf5 18.Nd6+ Kg6 19.Nd5 Kg5 20.c7 Kg4 21.c8=Q+ Kg3 22.Qc3+ Kf2 23.Ne4+ Kf1 24.Qf3+ Ke1 25.Qf2+ Kd1 26.Qd2#
6:21: +19.46/26 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.a7 Rg8 10.N3d5+ Kf7 11.a8=Q Rxa8 12.Nxa8 Ke6 13.Ndc7+ Ke7
6:21: #27/27 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.a7 Rg8 10.a8=Q Rg6+ 11.Kb7 Kf7 12.Qe8+ Kf6 13.Qe6+ Kg5 14.Qxg6+ Kxg6 15.N3b5 Kg5 16.c4 Kh5 17.c5 Kg5 18.Ne8 Kh4 19.c6 Kh3 20.c7 Kh4 21.Ned6 Kh5 22.c8=Q Kg5 23.Qf5+ Kh4 24.Nc7 Kg3 25.Ne4+ Kg2 26.Qf2+ Kh1 27.Ng3#
6:21: #27/28 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.a7 Rg8 10.a8=Q Rg6+ 11.Kb7 Kf7 12.Qe8+ Kf6 13.Qe6+ Kg5 14.Qxg6+ Kxg6 15.N3b5 Kg5 16.c4 Kh5 17.c5 Kg5 18.Ne8 Kh4 19.c6 Kh3 20.c7 Kh4 21.Ned6 Kh5 22.c8=Q Kg5 23.Qf5+ Kh4 24.Nc7 Kg3 25.Ne4+ Kg2 26.Qf2+ Kh1 27.Ng3#
6:21: #27/29 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.a7 Rg8 10.a8=Q Rg6+ 11.Kb7 Kf7 12.Qe8+ Kf6 13.Qe6+ Kg5 14.Qxg6+ Kxg6 15.N3b5 Kg5 16.c4 Kh5 17.c5 Kg5 18.Ne8 Kh4 19.c6 Kh3 20.c7 Kh4 21.Ned6 Kh5 22.c8=Q Kg5 23.Qf5+ Kh4 24.Nc7 Kg3 25.Ne4+ Kg2 26.Qf2+ Kh1 27.Ng3#
6:21: #26/30 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.a7 Rg8 10.a8=Q Rg6+ 11.Kb7 Kf7 12.Qe8+ Kf6 13.Qxg6+ Kxg6 14.N3b5 Kg5 15.c4 Kh5 16.c5 Kg5 17.Ne8 Kh4 18.c6 Kh3 19.c7 Kh4 20.Ned6 Kh5 21.c8=Q Kg5 22.Qf5+ Kh4 23.Nc7 Kg3 24.Ne4+ Kg2 25.Qf2+ Kh1 26.Ng3#
6:21: #26/31 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.a7 Rg8 10.a8=Q Rg6+ 11.Kb7 Kf7 12.Qe8+ Kf6 13.Qxg6+ Kxg6 14.N3b5 Kg5 15.c4 Kh5 16.c5 Kg5 17.Ne8 Kh4 18.c6 Kh3 19.c7 Kh4 20.Ned6 Kh5 21.c8=Q Kg5 22.Qf5+ Kh4 23.Nc7 Kg3 24.Ne4+ Kg2 25.Qf2+ Kh1 26.Ng3#
6:21: #26/32 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Nec7 Rb8 6.Nxa7+ Kd8 7.Nab5 Ke7 8.Nxc3 Rc8 9.a7 Rg8 10.a8=Q Rg6+ 11.Kb7 Kf7 12.Qe8+ Kf6 13.Qxg6+ Kxg6 14.N3b5 Kg5 15.c4 Kh5 16.c5 Kg5 17.Ne8 Kh4 18.c6 Kh3 19.c7 Kh4 20.Ned6 Kh5 21.c8=Q Kg5 22.Qf5+ Kh4 23.Nc7 Kg3 24.Ne4+ Kg2 25.Qf2+ Kh1 26.Ng3#
6:21: #21/33 1.Ne6 c5 2.Kb5 c4 3.Nxc4 Kc8 4.Kc6 Kb8 5.Nc7 Kc8 6.Nxa8 Kd8 7.Ncb6 Ke7 8.Nc8+ Kd8 9.Nxa7 Ke8 10.Nb5 Ke7 11.Kb6 Kf6 12.Nac7 Kf5 13.a7 Kf4 14.c4 Ke4 15.a8=Q+ Ke5 16.c5 Kf6 17.Qf3+ Kg5 18.Ne6+ Kg6 19.Qf4 Kh7 20.Qg5 Kh8 21.Qg7#
6:21: #21/34 1.Ne6 c5 2.Kb5 c4 3.Nxc4 Kc8 4.Kc6 Kb8 5.Nc7 Kc8 6.Nxa8 Kd8 7.Ncb6 Ke7 8.Nc8+ Kd8 9.Nxa7 Ke7 10.Nb5 Kf6 11.Nac7 Kg6 12.a7 Kh5 13.c4 Kg6 14.Kb6 Kf5 15.a8=Q Ke5 16.Ne6 Kxe6 17.Qf3 Ke5 18.Kc6 Ke6 19.Qf4 Ke7 20.Nc7 Kd8 21.Qf8#
6:21: #21/35 1.Ne6 c5 2.Kb5 c4 3.Nxc4 Kc8 4.Kc6 Kb8 5.Nc7 Kc8 6.Nxa8 Kd8 7.Ncb6 Ke7 8.Nc8+ Kd8 9.Nxa7 Ke7 10.Nb5 Kf6 11.Nac7 Kg6 12.a7 Kg5 13.Kb6 Kg6 14.a8=Q Kf5 15.Qf3+ Kg5 16.Kb7 Kh6 17.Qf6+ Kh5 18.Qf4 Kg6 19.Ne6 Kh7 20.Qf6 Kg8 21.Qg7#
6:21: #8/36 1.Ne6 c5 2.Kb5 c4 3.Kc6 c3 4.Nb5 Kc8 5.Kd6 Kb8 6.Nbd4 Kc8 7.Nc6 Rb8 8.Nxa7#
Given that SF found the first 4 moves in under a second, I think it would have found the M8 in a game: after playing the first 4 moves, it would now only need to find the M4.
Human chess is partly about tactics and strategy, but mostly about memory
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abik
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Re: Mate in 8 - hard for some easy for others

Post by abik »

These are fun test positions to look at!

Code: Select all

$ ./bikjump3.1
position fen rk6/p7/P1pN4/K1N5/8/8/2P5/8 w - - 0 1
go
...
info depth 1 seldepth 2 nodes 2 tbhits 0 time 0 score cp 209 pv c5d7
info depth 1 seldepth 3 nodes 16 tbhits 0 time 0 score cp 213 pv c5b7
info depth 2 seldepth 2 nodes 26 tbhits 0 time 1 score cp 206 pv c5b7  b8c7
info depth 2 seldepth 3 nodes 31 tbhits 0 time 1 score cp 347 pv c5e6  c6c5
info depth 3 seldepth 3 nodes 53 tbhits 0 time 1 score cp 347 pv c5e6  c6c5  e6c5
info depth 4 seldepth 8 nodes 265 tbhits 0 time 1 score cp 310 pv c5e6  c6c5  e6c5  b8c7  d6b5
info depth 5 seldepth 8 nodes 617 tbhits 0 time 1 score cp 310 pv c5e6  c6c5  e6c5  b8c7  d6b5  c7d8
info depth 6 seldepth 10 nodes 1354 tbhits 0 time 1 score cp 334 pv c5e6  c6c5  e6c5  b8c7  c5b7  a8h8  a5b4
info depth 7 seldepth 11 nodes 3032 tbhits 0 time 1 score cp 367 pv c5e6  c6c5  a5a4  c5c4  d6c4  b8c8  c4d6  c8d7
info depth 8 seldepth 12 nodes 6417 tbhits 0 time 2 score cp 356 pv c5e6  c6c5  c2c3  c5c4  d6c4  b8c8  c4e5  a8b8  a5a4
info depth 9 seldepth 14 nodes 14188 tbhits 1 time 5 score cp 361 pv c5e6  c6c5  d6b7  b8c8  c2c4  a8b8  e6c5  c8c7
info depth 10 seldepth 15 nodes 26004 tbhits 1 time 7 score cp 364 pv c5e6  c6c5  e6c5  b8c7  c5b7  a8h8  c2c4  h8h2  c4c5  c7d7
info depth 11 seldepth 16 nodes 44707 tbhits 2 time 11 score cp 364 pv c5e6  c6c5  e6c5  b8c7  c5b7  a8h8  c2c4  h8h2  c4c5  c7d7
info depth 12 seldepth 17 nodes 73923 tbhits 4 time 17 score cp 362 pv c5e6  c6c5  e6c5  b8c7  c5b7  a8h8  c2c4  h8h2  c4c5  c7d7
info depth 13 seldepth 20 nodes 122958 tbhits 13 time 27 score cp 1016 pv c5e6  c6c5  a5b5  c5c4  d6c4  b8c8  b5c6  c8b8  e6c7  b8c8
info depth 14 seldepth 17 nodes 153567 tbhits 14 time 32 score cp 1016 pv c5e6  c6c5  a5b5  c5c4  d6c4  b8c8  b5c6  c8b8  e6c7  b8c8
info depth 15 seldepth 18 nodes 212278 tbhits 16 time 43 score cp 1065 pv c5e6  c6c5  a5b5  c5c4  d6c4  b8c8  b5c6  c8b8  e6c7  b8c8
info depth 16 seldepth 24 nodes 328613 tbhits 27 time 63 score cp 1248 pv c5e6  c6c5  a5b5  c5c4  d6c4  b8c8  b5c6  c8b8  e6c7  b8c8
info depth 17 seldepth 23 nodes 489687 tbhits 49 time 92 score cp 1270 pv c5e6  c6c5  a5b5  c5c4  d6c4  b8c8  b5c6  c8b8  e6c7  b8c8
info depth 18 seldepth 23 nodes 734905 tbhits 131 time 135 score cp 1283 pv c5e6  c6c5  a5b5  c5c4  d6c4  b8c8  b5c6  c8b8  e6c7  b8c8
info depth 19 seldepth 24 nodes 1057084 tbhits 211 time 190 score cp 1304 pv c5e6  c6c5  a5b5  c5c4  d6c4  b8c8  b5c6  c8b8  e6c7  b8c8
info depth 20 seldepth 26 nodes 1674720 tbhits 463 time 299 score mate 8 pv c5e6  c6c5  a5b5  c5c4  b5c6  c4c3  d6b5  b8c8  c6d6  c8b8
bestmove c5e6  ponder c6c5
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