Mate in 8

[Spliffjiffer]

[D] 1RB1Nnr1/p7/K1k1p1p1/4pP1n/N1p1Pp2/1p1P2B1/b5r1/2b5 w - - 0 1

some engines might have problems, some other should be fast

[Haikouichthys]

Bh4!! Komodo 6 sees it after 11 seconds on my PC, running on two cores.
Nice combination.

[Ajedrecista]

Hello:

[D] 1RB1Nnr1/p7/K1k1p1p1/4pP1n/N1p1Pp2/1p1P2B1/b5r1/2b5 w - - 0 1

some engines might have problems, some other should be fast

Analysis by Critter 1.6a w32 (using four cores) in an Intel i5-760 (2.8 GHz) with 1 GB of hash and without Gaviota TB, running in console mode:

[...]

14/42 00:02 8790K 3658K +0.00 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
15/42 00:02 9263K 3705K +0.00 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
16/42 00:02 10288K 3840K +0.00 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:03 17063K 4361K +0.08 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:04 17523K 4342K +0.21 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:04 17948K 4322K +0.40 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:04 18542K 4306K +0.69 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:04 20533K 4290K +1.11 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:05 22080K 4275K +1.75 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:05 24786K 4273K +2.70 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:06 27039K 4282K +4.13 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:06 29903K 4312K +6.28 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:07 30759K 4319K +9.49 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:07 31468K 4341K +14.31 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42+ 00:07 31729K 4348K +21.54 Bh4 g5 Rb5 Ba3 Nb6 axb6 d4 exd4 Rxb6+ Kc5 Rb5+ Kc6 Rb6+
17/42 00:07 31896K 4353K +M8 Bh4 g5 Bxg5 R2xg5 Rb4 b2 Rb5 Be3 d4 Bxd4 Rd5 exd5 exd5+ Kxd5 Bb7#
18/42 00:07 32556K 4391K +M8 Bh4 g5 Bxg5 R2xg5 Rb4 b2 Rb5 Be3 d4 Bxd4 Rd5 exd5 exd5+ Kxd5 Bb7#
19/42 00:07 33620K 4455K +M8 Bh4 g5 Bxg5 R2xg5 Rb4 b2 Rb5 Be3 d4 Bxd4 Rd5 exd5 exd5+ Kxd5 Bb7#
20/42 00:07 37096K 4672K +M8 Bh4 g5 Bxg5 R2xg5 Rb4 b2 Rb5 Be3 d4 Bxd4 Rd5 exd5 exd5+ Kxd5 Bb7#
21/42 00:08 43147K 5027K +M8 Bh4 g5 Bxg5 R2xg5 Rb4 b2 Rb5 Be3 d4 Bxd4 Rd5 exd5 exd5+ Kxd5 Bb7#
22/42 00:10 57296K 5692K +M8 Bh4 g5 Bxg5 R2xg5 Rb4 b2 Rb5 Be3 d4 Bxd4 Rd5 exd5 exd5+ Kxd5 Bb7#
stop
bestmove Bh4 ponder g5

time: 11921 nodes: 76543593 evals: 53661441 knps: 6420
phash: 87.82% evalcache: 4.40% lazy: 68.10% eg_recog: 90
splits: 61157

Houdini 1.5a w32 also solved the position in a similar time in the same PC.

A very fast perft counter like JetChess is also able of solve some checkmate problems. Solution by JetChess 1.0.0.0 using 1 GB of hash in an Intel i5-760 (2.8 GHz):

Code: Select all

1RB1Nnr1/p7/K1k1p1p1/4pP1n/N1p1Pp2/1p1P2B1/b5r1/2b5 w - - 0 1

  1  Rb8-a8   0
  2  Rb8-b7   0
  3  Rb8-b6   0
  4  Rb8-b5   0
  5  Rb8-b4   0
  6  Rb8*b3   0
  7  Bg3*f4   0
  8  Bg3-h4   Mate
  9  Bg3-h2   0
 10  Bg3-f2   0
 11  Bg3-e1   0
 12  Bc8-d7   0
 13  Bc8*e6   0
 14  Bc8-b7   0
 15  Na4-b6   0
 16  Na4-c5   0
 17  Na4-b2   0
 18  Na4-c3   0
 19  Ne8-c7   0
 20  Ne8-d6   0
 21  Ne8-f6   0
 22  Ne8-g7   0
 23   d3-d4   0
 24   d3*c4   0
 25   f5-f6   0
 26   f5*e6   0
 27   f5*g6   0
 28  Ka6*a7   0
 29  Ka6-a5   0

Solution:  Bg3-h4  (mate in 8)

Time: 420.472 s

Code: Select all

1RB1Nnr1/p7/K1k1p1p1/4pP1n/N1p1Pp2/1p1P2B1/b5r1/2b5 w - - 0 1

  1  Rb8-a8   0
  2  Rb8-b7   0
  3  Rb8-b6   0
  4  Rb8-b5   0
  5  Rb8-b4   0
  6  Rb8*b3   0
  7  Bg3*f4   0
  8  Bg3-h4   0
  9  Bg3-h2   0
 10  Bg3-f2   0
 11  Bg3-e1   0
 12  Bc8-d7   0
 13  Bc8*e6   0
 14  Bc8-b7   0
 15  Na4-b6   0
 16  Na4-c5   0
 17  Na4-b2   0
 18  Na4-c3   0
 19  Ne8-c7   0
 20  Ne8-d6   0
 21  Ne8-f6   0
 22  Ne8-g7   0
 23   d3-d4   0
 24   d3*c4   0
 25   f5-f6   0
 26   f5*e6   0
 27   f5*g6   0
 28  Ka6*a7   0
 29  Ka6-a5   0

No mate in 7 moves

Time: 55.631 s

Regards from Spain.

Ajedrecista.

[zullil]

Bh4!! Komodo 6 sees it after 11 seconds on my PC, running on two cores.
Nice combination.

What does "sees it" mean?

With 8 cores and 1GB hash, Komodo 6 gave me:

Code: Select all

info depth 24 time 24914 nodes 204671843 score mate 18 lowerbound nps 8215133 hashfull 600 pv g3h4 
info currmove g3h4 currmovenumber 1
info depth 24 time 582052 nodes 5736299877 score mate 8 nps 9855304 hashfull 936 pv g3h4 g6g5 h4g5 g2g5 b8b4 b3b2 b4b5 c1e3 d3d4 e3d4 b5d5 e6d5 e4d5 c6d5 c8b7 

25 seconds to reach a mate score, but almost 10 minutes to reach mate-in-8!

[EDIT] Here's a second try:

Code: Select all

info depth 25 time 49058 nodes 415214699 score mate 20 lowerbound nps 8463751 hashfull 601 pv g3h4 
info currmove g3h4 currmovenumber 1
info depth 25 time 132249 nodes 1091404159 score mate 8 nps 8252645 hashfull 925 pv g3h4 g6g5 h4g5 g2g5 b8b4 b3b2 b4b5 c1e3 d3d4 e3d4 b5d5 e6d5 e4d5 c6d5 c8b7