How hard it is to win with Black...

[Guenther]

First time after a very long period I tried again a 20b net with LC0 on my slow GPU vs. a recent SF dev build.
(last NN40 nets seem to be the strongest meanwhile surpassing all previous nets)
Of course a sufficiently slow tc (1800+30) also was needed, otherwise LC0 had no chance on my hardware (see pgn header).

The game was quite interesting for various aspects.

SF played the opening really poor, I don't like how the piece development culminated in a setup with Nh4/Bh3
(the Bishop remained nearly locked for a long time) and also wasting a tempo, with playing d3 and soon after d4.

There were some astonishing blind spots in both opponents evals, while watching.
SF never considered the simple 11...g6 after Nh4 and instead always predicted the weaker 11...Ng4?!
LC0 never considered 35. h4! and always predicted 35. hxg4?! instead.
(h4! is much better leaving nearly a kind of festung and also fixes Blacks Kside pawns to be vulnerable
for certain variations)

I wonder most though, why SF still out of nowhere, received a heavy fail low after 50...Kc7?
[d]8/2k5/2p1b3/5p1p/1pP1pPpP/1P2P1K1/r4P2/3R1B2 w - - 7 51
I can only imagine some sacrifices on c4 with an active King, but how should that work?
There is no log saved, so I don't know what SF had seen here?

Edit: With a few multicore analysis attempts I finally could see the winning plan!
c5-Kb6-Ka5-Bd7-Ba4! (order depends on Whites interim moves), while White is practically paralyzed and will be crushed on the Q-side, no matter if the B-sac is refused or accepted.
No idea how long it would take LC0 to see that plan on my hardware.

After the attempt 53...g3! and last after 60...Kc5? instead of Ke7 the win was blown.

[pgn][Event "Test 2019"] [Site "RWBC Win7U-64 Q8200 2.33Ghz Nvidia GT 710"] [Date "2019.05.05"] [Round "1"] [White "Stockfish_19042419-64"] [Black "LC0_0211-ID42232"] [Result "1/2-1/2"] [ECO "A20"] [Opening "English, Nimzovich Variation"] [PlyCount "171"] [Termination "adjudication"] [TimeControl "1800+30"] 1. c4 {book} e5 {book} 2. Nf3 {book} d6 {book} 3. Nc3 {book} f5 {book} 4. g3 {+0.60/28 121.9s} Be7 {-0.48/8 49.51s} 5. d3 {+0.52/27 41.68s} a5 {-0.29/8 67.90s} 6. Bh3 {+0.52/25 45.68s} Nf6 {-0.21/9 79.80s} 7. d4 {+0.75/28 199.7s} Nc6 {-0.15/10 23.70s} 8. dxe5 {+0.64/26 30.79s} dxe5 {+0.36/9 52.10s} 9. Qxd8+ {+0.51/31 83.43s} Bxd8 {+0.27/9 40.40s} 10. b3 {+0.53/30 77.31s} e4 {+0.56/9 79.20s} 11. Nh4 {+0.36/30 76.32s} g6 {+0.55/9 50.61s} 12. O-O {+0.09/29 191.0s} O-O {+0.60/8 60.91s} 13. Rd1 {+0.50/27 37.66s} Nb4 {+0.60/8 91.60s} 14. Ng2 {+0.51/27 63.57s} c6 {+0.62/8 135.0s} 15. Na4 {0.00/34 248.2s} Be6 {+0.66/8 47.61s} 16. Nf4 {0.00/31 41.66s} Bf7 {+0.79/10 43.70s} 17. Bb2 {+0.07/32 90.26s} Be7 {+1.20/9 52.40s} 18. a3 {-0.07/29 33.85s} Na6 {+0.95/10 64.11s} 19. Bf1 {-0.28/33 124.2s} g5 {+1.13/9 88.10s} 20. Ng2 {-0.16/25 14.94s} Be6 {+1.11/10 33.50s} 21. Ne3 {0.00/27 45.26s} Kf7 {+1.17/10 63.00s} 22. Bc3 {-0.18/27 88.56s} b5 {+1.18/12 77.01s} 23. Nb6 {-0.15/25 22.96s} Rad8 {+1.24/12 33.60s} 24. Bh3 {-0.79/27 77.36s} g4 {+2.30/11 90.41s} 25. Bf1 {-0.83/29 36.37s} Rxd1 {+2.56/13 56.40s} 26. Rxd1 {-1.49/32 69.89s} b4 {+2.58/15 44.11s} 27. axb4 {-1.39/33 24.57s} axb4 {+2.63/14 36.51s} 28. Bxf6 {-1.43/36 80.11s} Kxf6 {+2.81/14 58.20s} 29. Na4 {-1.39/37 28.71s} Nc5 {+5.99/10 106.9s} 30. Nxc5 {-1.38/38 28.70s} Bxc5 {+5.51/11 42.60s} 31. Ng2 {-1.38/39 33.50s} Ra8 {+5.69/10 58.20s} 32. Nf4 {-1.38/41 37.37s} Ra2 {+6.68/9 89.60s} 33. Rb1 {-1.38/38 29.33s} Bf7 {+7.99/9 83.51s} 34. h3 {-1.36/38 65.13s} h5 {+7.73/10 68.70s} 35. h4 {-1.29/41 25.74s} Bd4 {+9.18/8 153.0s} 36. e3 {-1.28/45 31.40s} Be5 {+8.91/8 15.61s} 37. Ne2 {-1.28/47 29.96s} Ke7 {+9.03/7 104.8s} 38. Nf4 {-1.28/48 39.58s} Kd8 {+9.07/7 82.70s} 39. Kg2 {-1.28/47 34.25s} Kc7 {+8.32/7 65.52s} 40. Kg1 {-1.28/48 32.51s} Rd2 {+8.02/7 56.90s} 41. Kg2 {-1.28/49 45.57s} Kd6 {+7.08/7 64.30s} 42. Kg1 {-1.28/46 29.93s} Ra2 {+6.62/7 63.40s} 43. Ne2 {-1.28/49 42.98s} Rc2 {+6.66/6 57.50s} 44. Nf4 {-1.28/47 34.56s} Rd2 {+6.62/8 53.10s} 45. Ne2 {-1.28/49 35.32s} Be6 {+6.22/7 66.10s} 46. Nf4 {-1.28/49 27.37s} Bxf4 {+5.94/8 48.30s} 47. gxf4 {-0.92/45 26.99s} Kd7 {+5.41/8 61.80s} 48. Kg2 {-0.92/50 29.16s} Rc2 {+4.66/7 53.00s} 49. Kg3 {-0.92/47 32.62s} Ra2 {+4.19/7 51.60s} 50. Rd1+ {-0.92/48 32.44s} Kc7 {+4.00/8 27.20s} 51. Rb1 {-2.54/50 284.4s} Rc2 {+3.57/7 69.40s} 52. Kg2 {-3.94/39 92.77s} Bc8 {+3.42/7 44.30s} 53. Kg1 {-3.94/36 121.7s} g3 {+3.80/7 37.20s} 54. fxg3 {-1.56/29 15.46s} Be6 {+3.92/9 22.00s} 55. Bg2 {-1.62/32 24.74s} Re2 {+2.98/10 35.80s} 56. g4 {-1.64/31 27.45s} fxg4 {+2.49/12 75.21s} 57. Bxe4 {-2.00/34 86.44s} Bf7 {+2.85/11 22.40s} 58. Bh7 {-1.94/31 26.73s} Rxe3 {+4.37/8 29.40s} 59. Kg2 {-1.85/33 30.49s} Kd6 {+5.58/10 34.00s} 60. Rd1+ {-2.90/34 49.45s} Kc5 {+5.72/11 28.80s} 61. Rd7 {-0.71/33 10.68s} Be6 {+5.95/11 28.30s} 62. Rd3 {-0.70/40 20.41s} Rxd3 {+5.55/11 25.50s} 63. Bxd3 {-0.59/43 16.50s} Bf7 {+4.96/13 12.10s} 64. Kf2 {-0.50/44 14.92s} Kd4 {+1.66/14 47.11s} 65. Bh7 {-0.58/47 34.94s} Be8 {+1.28/14 36.49s} 66. Kg3 {-0.59/48 15.96s} c5 {+2.10/12 78.30s} 67. Kf2 {0.00/44 15.92s} Bc6 {+1.81/12 36.90s} 68. Bg6 {0.00/45 18.29s} Bf3 {+1.69/17 5.60s} 69. Bxh5 {0.00/46 18.59s} Bd1 {+1.42/18 11.70s} 70. Bg6 {0.00/48 25.29s} Bxb3 {+1.08/17 25.01s} 71. h5 {0.00/50 25.35s} Bxc4 {+1.06/14 10.20s} 72. h6 {0.00/49 22.47s} Bg8 {+0.48/15 31.70s} 73. Kg3 {0.00/50 24.12s} c4 {+0.21/16 52.41s} 74. Kxg4 {0.00/42 19.26s} b3 {+0.04/15 27.00s} 75. Kf3 {0.00/45 24.41s} Kc3 {+0.06/13 24.40s} 76. f5 {0.00/47 20.79s} Kd2 {+0.08/14 34.11s} 77. f6 {0.00/49 23.49s} c3 {+0.06/12 24.10s} 78. f7 {0.00/52 50.56s} Bxf7 {+0.05/11 32.60s} 79. h7 {0.00/57 25.30s} Bxg6 {+0.04/10 33.99s} 80. h8=Q {0.00/60 18.78s} b2 {+0.06/8 17.71s} 81. Qh2+ {0.00/64 28.73s} Kc1 {+0.06/9 87.30s} 82. Qh1+ {0.00/71 19.50s} Kc2 {+0.05/9 30.11s} 83. Qg2+ {0.00/68 54.05s} Kc1 {+0.04/8 45.90s} 84. Qh1+ {0.00/73 20.40s} Kc2 {+0.08/8 36.90s} 85. Qg2+ {0.00/68 35.09s} Kc1 {+0.06/5 22.70s} 86. Qf1+ {0.00/86 63.06s, Draw by adjudication: user decision} 1/2-1/2[/pgn]