A practical position

[Look]

Hi,

I was casually watching an engine vs engine game. This position occurred:


[fen]7k/p5bP/bp4q1/2p1r1B1/P1p2Q1P/5P2/4NKP1/3R4 b - - 0 23[/fen]


What is your take on it ?

[Look]

Sorry I can not get the fen right.

[Eelco de Groot]

Hi Mehdi, do you mean this is not the position you remembered? Or you don't see a diagram? It looks a plausible position, but a diagram only appears with http://, but not with https://


To make it more complicated, some browsers automatically redirect you to https:// and you may not realize it... On top of that Cloudflare needs to know you are a human first etc...

[Look]

Hi Mehdi, do you mean this is not the position you remembered? Or you don't see a diagram? It looks a plausible position, but a diagram only appears with http://, but not with https://


To make it more complicated, some browsers automatically redirect you to https:// and you may not realize it... On top of that Cloudflare needs to know you are a human first etc...

I mean , can't see the diagram properly in https. I hope this is fixed too.

[towforce]

I mean , can't see the diagram properly in https.

You could post the game as a PGN like this:


[pgn]1. e4 e5 2. Nf3 Nc6 3. Bb5 Bc5 4. c3 Nf6 5. O-O O-O 6. d4 Bb6 7. a4 a6 8. Bxc6 dxc6 9. Nxe5 Nxe4 10. Re1 Nd6 11. a5 Ba7 12. Be3 Be6 13. Nf3 f6 14. b4 Nb5 15. Qc2 Qd7 16. Nbd2 Rfe8 17. Rad1 Rad8 18. c4 Bf5 19. Qb3 Be6 20. Kh1 Bf7 21. Qb2 Nd6 22. Rc1 Bh5 23. h3 h6 24. Qc2 Qf7 25. Kh2 g5 26. c5 Bg6 27. Qb2 Nf5 28. Nf1 Ne7 29. Bd2 Nd5 30. Ng3 Qd7 31. Ng1 h5 32. f3 h4 33. Ne4 Qf5 34. Ne2 Bh5 35. Rf1 Bf7 36. N2c3 Be6 37. Rce1 Qg6 38. Nd1 Bf5 39. Ne3 Bxe4 40. fxe4 Rxe4 41. Qb1 Kh7 42. Nf5 Ree8 43. Re4 Rxe4 44. Qxe4 Re8 45. Qg4 Rg8 46. Rf3 Rh8 47. Be1 Kg8 48. Nxh4 Qf7 49. Nf5 Qh5 50. Qe4 Kf8 51. Bd2 Qe8 52. Qd3 Qg6 53. Rf1 Rh7 54. g4 Bb8 55. Qe2 Qe8 56. Qf3 Qg6 57. h4 Ke8 58. h5 b6 59. Ng3 Kd7 60. Ne4 Rh6 61. Kg1 Qg8 62. cxb6 cxb6 63. axb6 Bf4 64. Nc5+ Kd8 65. b7 Kc7 66. Qa3 Bxd2 67. Nxa6+ Kd6 68. b8=Q+ Qxb8 69. Nxb8 Rh7 70. b5+ Ke6 71. Nxc6 Rd7 72. Qf8 Nf4 73. Rd1 Be3+ 74. Kf1 Nd5 75. Ra1 Nb6 76. Ke2 Bxd4 77. Rd1 Bc5 78. Qg8+ Rf7 79. Nd8+ Ke5 80. Kf3 Bd4 81. Qxf7 Kd6 82. Nb7+ Ke5 83. Qe8+ Kd5 84. Qc6+ Ke5 85. Qd6#*[/pgn]

[Ajedrecista]

Hello:

Hi,

I was casually watching an engine vs engine game. This position occurred:


[fen]7k/p5bP/bp4q1/2p1r1B1/P1p2Q1P/5P2/4NKP1/3R4 b - - 0 23[/fen]


What is your take on it ?

There are three reasonable moves according to SF 15.1 at shallow depths: 23.- ..., Re8, 23.- ..., Rxe2+ and 23.- ..., Kxh7, with 23.- ..., c3 replacing 23.- ..., Rxe2+ at higher depths.

Code: Select all

FEN: 7k/p5bP/bp4q1/2p1r1B1/P1p2Q1P/5P2/4NKP1/3R4 b - - 0 23

Stockfish_15.1-x64-modern:
[...]
---------------------------------------------------------------------------
 45/57	14:50	3.172.967.067	3.565.766	-1,28	Re5xe2+ Kf2xe2 Qg6c2+ Ke2e1 Bg7c3+ Rd1d2 Bc3xd2+ Qf4xd2 Qc2xd2+ Bg5xd2 Ba6c8 Bd2f4 Bc8e6 Bf4b8 a7a6 Bb8a7 c4c3 Ba7xb6 c3c2 Ke1d2 Be6c4 Bb6xc5 Bc4f1 g2g4 Bf1e2 g4g5 Kh8xh7 f3f4 Kh7g6 Kd2xc2 Kg6f5 Bc5e3 Be2h5 Be3d2 Bh5e8 a4a5 Kf5e4 Kc2c3 Be8f7 Bd2c1 Ke4d5 f4f5 Kd5e5 f5f6 Ke5e4 Bc1d2 Ke4d5 Kc3d3 Kd5e5 Bd2e3 Ke5d5 Be3c1 Bf7h5 Bc1d2 Bh5g6+ Kd3e3 Bg6e8
 45/65	14:50	3.172.967.067	3.565.766	-0,20	Kh8xh7 Ne2g3 Qg6e6 Ng3e4 c4c3 Rd1d8 c3c2 Ne4f6+ Bg7xf6 Bg5xf6 Re5e2+ Kf2g3 c2c1Q Rd8h8+ Kh7g6 Qf4xc1 Qe6d6+ Kg3h3 Kg6f7 Bf6a1 Qd6e6+ Kh3g3 Qe6d6+ Qc1f4+ Qd6xf4+ Kg3xf4 Re2xg2 Rh8h7+ Kf7e6 Rh7xa7 Ba6d3 Ra7b7 Rg2a2 Rb7xb6+ Ke6d5 Ba1c3 Ra2a3 Bc3b2 Ra3xa4+ Kf4g5 Ra4b4 Rb6xb4 c5xb4 Kg5f6 Bd3c2 h4h5 Bc2d1 h5h6 Bd1c2 Bb2c1 b4b3 Bc1b2 Bc2d3 Bb2c3 Bd3h7 Kf6f7
 45/60	14:50	3.172.967.067	3.565.766	-0,12	Re5e8 Rd1d6 Qg6c2 Kf2g3 Qc2xe2 Bg5f6 Qe2e1+ Kg3h2 Qe1e5 Qf4xe5 Re8xe5 Rd6d8+ Kh8xh7 Rd8d7 Kh7g6 Bf6xg7 Re5h5 Bg7c3 Rh5xh4+ Kh2g3 Rh4h7 Rd7d6+ Kg6f7 a4a5 Kf7e7 Rd6g6 Ba6b7 a5xb6 a7xb6 Rg6xb6 Bb7d5 Rb6a6 Rh7h1 Ra6a1 Rh1xa1 Bc3xa1 Ke7e6 Kg3f4 Bd5c6 Ba1g7 Bc6d5 Bg7c3 Bd5b7 Kf4e3 Bb7d5 Bc3e1 Ke6e7 g2g4 Ke7f7 Be1c3 Bd5b7 f3f4 Kf7g6 Bc3e5
---------------------------------------------------------------------------
 46/83	31:43	6.855.711.991	3.600.899	-1,80	c4c3 Ne2xc3 Ba6d3 Bg5h6 Qg6xh6 Qf4xh6 Bg7xh6 Rd1xd3 Re5e7 Nc3e4 Kh8xh7 g2g4 Re7c7 Ne4f6+ Kh7g6 Nf6e8 Rc7e7 h4h5+ Kg6h7 Ne8f6+ Kh7g7 Nf6e4 Bh6f4 Rd3d8 Re7c7 Kf2e2 c5c4 Ke2d1 a7a6 g4g5 Bf4e5 Rd8d5 Be5f4 Rd5f5 Bf4e3 Kd1c2 b6b5 a4xb5 a6xb5 Rf5xb5 Rc7a7 Kc2c3 Ra7f7 Rb5b8 Rf7d7 Ne4f6 Rd7d3+ Kc3xc4 Be3xg5
 46/64	31:43	6.855.711.991	3.600.899	-0,31	Kh8xh7 Ne2g3 Qg6e6 Rd1d8 c4c3 Ng3e4 c3c2 Ne4f6+ Bg7xf6 Bg5xf6 Re5e2+ Kf2g3 c2c1Q Rd8h8+ Kh7g6 Qf4xc1 Qe6d6+ Kg3h3 Kg6f7 Bf6a1 Qd6e6+ Kh3g3 Qe6d6+ Qc1f4+ Qd6xf4+ Kg3xf4 Re2xg2 Rh8h7+ Kf7e6 Rh7xa7 Ba6d3 Ba1c3 Rg2c2 Bc3h8 Rc2a2 Kf4g3 b6b5 Ra7a6+ Ke6e7 a4xb5 Ra2xa6 b5xa6 Bd3xa6 Bh8c3 Ke7f7 h4h5 Ba6d3 Kg3g4 Kf7e7 Kg4g5 Ke7e6 Bc3e1 Bd3c2 h5h6 Bc2f5
 46/56	31:43	6.855.711.991	3.600.899	-0,16	Re5e8 Rd1d6 Qg6c2 Kf2g3 Qc2xe2 Bg5f6 Qe2e1+ Kg3h2 Qe1e5 Qf4xe5 Re8xe5 Rd6d8+ Kh8xh7 Rd8d7 Kh7g6 Bf6xg7 Re5h5 Bg7c3 Rh5xh4+ Kh2g3 Rh4h7 Rd7d6+ Kg6f7 a4a5 Kf7e7 Rd6g6 Ba6c8 a5xb6 a7xb6 Rg6xb6 Bc8e6 Kg3f4 Be6d5 Rb6a6 Rh7h2 Ra6a2 Rh2h1 Ra2e2+ Ke7d6 Re2e3 Rh1d1 Bc3h8 Kd6d7 g2g4 Kd7d6 Bh8b2 Rd1d3 g4g5 Rd3xe3 Kf4xe3

23.- ..., Rxe2+ is tempting in an attempt to trade pieces and hope to get an OCB endgame. After 23.- ..., Rxe2+; 24.- Kxe2, Qc2+; 25.- Ke1, Bc3+; 26.- Rd2, Bxd2+; 27.- Qxd2, Qxd2+; 28.- Bxd2, SF 15.1 returns +1.90 evals without clearing hash from the previous search. Clearing hash and trying to deviate with 28.- ..., Kxh7 instead of the proposed 28.- ..., Bc8, SF 15.1 initially liked 29.- Bf4, but later changed to 29.- Kf2:

Code: Select all

FEN: 8/p6k/bp6/2p5/P1p4P/5P2/3B2P1/4K3 w - - 0 29

Stockfish_15.1-x64-modern:
Found 145 tablebases
classical evaluation enabled
[...]
 41/46	00:27	 120.204.920	4.391.207	+0,85	Bd2f4 c4c3 Bf4b8 b6b5 a4xb5 Ba6xb5 Bb8e5 c3c2 Be5b2 Bb5c6 Ke1f2 Bc6d7 g2g4 Kh7h6 Bb2a3 Bd7c8 h4h5 Bc8d7 Ba3c1+ Kh6g7 Kf2e3 a7a5 Ke3f2 a5a4 Kf2g3 Bd7b5 Bc1a3 Kg7h6 Kg3h4 Kh6g7 Ba3b2+ Kg7h7 g4g5 Bb5e8 g5g6+ Be8xg6 h5xg6+ Kh7xg6 Kh4g4 Kg6h6
 42/39+	00:32	 141.424.378	4.413.167	+0,87	Bd2f4
 42/42+	00:36	 161.115.291	4.432.210	+0,91	Bd2f4
 42/47+	00:45	 201.444.348	4.466.120	+1,04	Bd2f4
 42/55	00:47	 208.763.918	4.466.111	+0,84	Bd2f4 c4c3 Bf4b8 Kh7g6 Bb8xa7 Kg6h5 Ba7xb6 Kh5xh4 Bb6c7 c3c2 Ke1d2 Ba6f1 g2g3+ Kh4h3 a4a5 Bf1e2 Kd2xc2 Be2xf3 a5a6 Bf3e4+ Kc2d2 Be4d5 Bc7d6 Kh3g4 Kd2e3 Bd5c6 a6a7 Bc6b7 Ke3d3 Kg4f5 Kd3c4 Kf5g4 Bd6f4 Kg4f5 Bf4b8 Kf5g4 Kc4xc5 Bb7f3
 43/35+	00:49	 220.853.984	4.463.500	+0,94	Bd2f4
 43/48+	00:51	 229.887.415	4.466.608	+0,99	Bd2f4
 43/48-	00:53	 237.383.518	4.468.143	+0,85	Bd2f4 c4c3
 43/48-	00:55	 247.753.709	4.464.513	+0,36	Bd2f4 c4c3
 43/57+	01:31	 397.564.152	4.342.258	+0,50	Ke1d1
 43/57+	01:44	 451.407.975	4.323.458	+0,78	Ke1f2
 43/60+	03:58	1.029.925.540	4.331.258	+2,88	Ke1f2
 43/68	05:00	1.298.388.002	4.332.234	+3,25	Ke1f2 Ba6b7 a4a5 Kh7g6 a5xb6 a7xb6 g2g4 Bb7d5 h4h5+ Kg6f6 Kf2g3 Bd5g8 f3f4 b6b5 Bd2e3 c4c3 Be3xc5 Kf6e6 Bc5b4 c3c2 Bb4d2 b5b4 f4f5+ Ke6d5 h5h6 Kd5c4 Bd2c1 Kc4c3 f5f6 b4b3 f6f7 b3b2 Bc1xb2+ Kc3xb2 f7xg8Q c2c1Q Qg8b8+ Kb2a2 Qb8a8+ Ka2b2 Qa8b7+ Kb2a3 Qb7a6+ Ka3b2
 44/60+	05:32	1.435.529.445	4.321.683	+3,25	Ke1f2
 44/60+	06:23	1.662.147.112	4.339.855	+3,49	Ke1f2
 44/63+	17:21	4.735.346.156	4.545.865	+5,26	Ke1f2
 44/70	22:22	6.143.549.419	4.575.729	+5,37	Ke1f2 Ba6b7 a4a5 c4c3 Bd2xc3 b6b5 g2g4 Kh7g6 h4h5+ Kg6f7 Bc3e5 Bb7c6 Be5d6 c5c4 Bd6c5 a7a6 Bc5b4 Bc6e8 Kf2g3 Kf7g8 Bb4c3 Be8f7 f3f4 Bf7e8 f4f5 Kg8h7 Kg3h4 Be8d7 Kh4g5 Bd7e8 Bc3b4 Be8d7 Kg5f4 Bd7e8 Kf4e5 Kh7g7 Bb4d2 Kg7h7 Ke5f6 b5b4

There were 7,043,767 TB hits to the full set of 3, 4 and 5-man Syzygy EGTB.

So, the Rxe2+ simplification is risky for black and maybe losing. People with faster hardware and better analysis skills would bring better analysis.

I have just accidentally saw that NNUE eval was not used in both analysis, though they should be still valid. With NNUE, SF 15.1 sees 29.- a5 and 29.- Kf2 faster as winning moves. Coming back to the original position, SF 15.1 with NNUE enabled still thinks that 23.- ..., Re8 is the best move. This position is unpleasant to play with black.

Regards from Spain.

Ajedrecista.