TCEC bonus started with balanced lines

Currently running on TCEC:

A bonus match between Leela and Stockfish. 100 games with 50 balanced lines.

https://tcec-chess.com/#

Note: an earlier 100 game bookless match between SF and Leela ended in 100 draws.

Jeroen_TCEC wrote:

Note: an earlier 100 game bookless match between SF and Leela ended in 100 draws.

Final result of the TCEC Balanced lines bonus:

Stockfish - Leela Chess Zero  50.5 - 49.5

There were 3 wins and 97 draws. White wins in the French, the Scandinavian and the Benko gambit.

First TCEC event with balanced lines and I really enjoyed it. Very high quality theoretical games and a nice change from all events with unbalanced openings.

Here is the Stockfish loss, with quite some interesting moments. Book ended after 4... c5 and with best play white doesn't have much. F.e. Leela drew easily with black after 5. a3 Ba5. But also SF's 5... Bxc3+ is theoretically sound and should lead to a draw.

First critical move is 7... Nf5?!, which is not the best. 7... Qc7 is usual and only gives white a slight edge, although that needs some deep calculation. Then Stockfish makes a very instructive mistake: 9... Qh4? This overlooks a develish trap (which, by the way, is in my Rebel books). After white's 11. Nf3! SF suddenly notices that 11... Qxg2 12. Ke2!! is not good for black, as 12... Qxh1 13. Qg5! traps the queen on h1 (Bb2 is coming). According to the engines this is lost for white.

Hence SF tries to bail out with 11... h4, but the damage was already done and Leela won an excellent game. Note the excellent 14. Rg1! and 15. g4! pushing black back. On move 36 SF makes life easy for white by giving up a bishop, but according to the engines white was already completely winning at that point.

[Event "TCEC Season 26 - Balanced Lines Bonus"]
[Site "https://tcec-chess.com"]
[Date "2024.08.01"]
[Round "13.1"]
[White "LCZero 0.31-dag-5350a2e-BT4-61"]
[Black "Stockfish dev-20240728-2343f71"]
[Result "1-0"]
[ECO "C19"]
[WhiteElo "3631"]
[BlackElo "3662"]
[PlyCount "145"]
[EventDate "2024.??.??"]

1. e4 e6 2. d4 d5 3. Nc3 Bb4 4. e5 c5 5. a3 Bxc3+ 6. bxc3 Ne7 7. Qg4 Nf5 8. Bd3 h5 9. Qf4 Qh4 10. Qd2 Qg4 11. Nf3 h4 12. Be2 Qg6 13. a4 c4 14. Rg1 Bd7 15. g4 hxg3 16. fxg3 Nc6 17. Ba3 a5 18. Kd1 f6 19. h4 fxe5 20. h5 Qh6 21. g4 Ne3+ 22. Kc1 exd4 23. Nxd4 Nxd4 24. Qxd4 Nf5+ 25. Qd2 Qxd2+ 26. Kxd2 Nh6 27. g5 Nf5 28. Bg4 O-O-O 29. Bc5 e5 30. h6 gxh6 31. Bxf5 Bxf5 32. g6 Rhg8 33. g7 b6 34. Be7 Rde8 35. Ba3 Bh3 36. Rg3 Re6 37. Rxh3 Rxg7 38. Re1 Rg2+ 39. Kc1 Kb7 40. Kb1 Rf6 41. Bb2 e4 42. Rh5 e3 43. Rxe3 d4 44. cxd4 Rf1+ 45. Ka2 Rxc2 46. Rc3 Re2 47. Rxc4 Rff2 48. Rb5 h5 49. d5 Rf6 50. Kb3 Rd6 51. Rf4 Rg6 52. Kc4 Rc2+ 53. Kd3 Rcg2 54. Be5 R2g3+ 55. Ke4 Ra3 56. Kf5 Rag3 57. d6 R3g5+ 58. Ke4 Kc6 59. Rb3 Kb7 60. d7 Rg8 61. Rf6 Rg4+ 62. Kd5 Rb4 63. Rc3 Rd8 64. Rc7+ Ka6 65. Rd6 h4 66. Rc8 Rxd7 67. Rxd7 Rxa4 68. Rc1 h3 69. Kc6 h2 70. Bxh2 Rg4 71. Bg1 Rg6+ 72. Rd6 Rxd6+ 73. Kxd6 1-0

[pgn]
[Event "TCEC Season 26 - Balanced Lines Bonus"]
[Site "https://tcec-chess.com"]
[Date "2024.08.01"]
[Round "13.1"]
[White "LCZero 0.31-dag-5350a2e-BT4-61"]
[Black "Stockfish dev-20240728-2343f71"]
[Result "1-0"]
[ECO "C19"]
[WhiteElo "3631"]
[BlackElo "3662"]
[PlyCount "145"]
[EventDate "2024.??.??"]

1. e4 e6 2. d4 d5 3. Nc3 Bb4 4. e5 c5 5. a3 Bxc3+ 6. bxc3 Ne7 7. Qg4 Nf5 { First critical move is 7... Nf5?!, which is not the best. 7... Qc7 is usual and only gives white a slight edge, although that needs some deep calculation.} 8. Bd3 h5 9. Qf4 Qh4 {Then Stockfish makes a very instructive mistake: 9... Qh4? This overlooks a develish trap (which, by the way, is in my Rebel books).} 10. Qd2 Qg4 11. Nf3 {SF suddenly notices that 11... Qxg2 12. Ke2!! is not good for black, as 12... Qxh1 13. Qg5! traps the queen on h1 (Bb2 is coming). According to the engines this is lost for white.} h4 {Hence SF tries to bail out with 11... h4, but the damage was already done and Leela won an excellent game. Note the excellent 14. Rg1! and 15. g4! pushing black back. On move 36 SF makes life easy for white by giving up a bishop, but according to the engines white was already completely winning at that point.} 12. Be2 Qg6 13. a4 c4 14. Rg1 Bd7 15. g4 hxg3 16. fxg3 Nc6 17. Ba3 a5 18. Kd1 f6 19. h4 fxe5 20. h5 Qh6 21. g4 Ne3+ 22. Kc1 exd4 23. Nxd4 Nxd4 24. Qxd4 Nf5+ 25. Qd2 Qxd2+ 26. Kxd2 Nh6 27. g5 Nf5 28. Bg4 O-O-O 29. Bc5 e5 30. h6 gxh6 31. Bxf5 Bxf5 32. g6 Rhg8 33. g7 b6 34. Be7 Rde8 35. Ba3 Bh3 36. Rg3 Re6 37. Rxh3 Rxg7 38. Re1 Rg2+ 39. Kc1 Kb7 40. Kb1 Rf6 41. Bb2 e4 42. Rh5 e3 43. Rxe3 d4 44. cxd4 Rf1+ 45. Ka2 Rxc2 46. Rc3 Re2 47. Rxc4 Rff2 48. Rb5 h5 49. d5 Rf6 50. Kb3 Rd6 51. Rf4 Rg6 52. Kc4 Rc2+ 53. Kd3 Rcg2 54. Be5 R2g3+ 55. Ke4 Ra3 56. Kf5 Rag3 57. d6 R3g5+ 58. Ke4 Kc6 59. Rb3 Kb7 60. d7 Rg8 61. Rf6 Rg4+ 62. Kd5 Rb4 63. Rc3 Rd8 64. Rc7+ Ka6 65. Rd6 h4 66. Rc8 Rxd7 67. Rxd7 Rxa4 68. Rc1 h3 69. Kc6 h2 70. Bxh2 Rg4 71. Bg1 Rg6+ 72. Rd6 Rxd6+ 73. Kxd6 1-0[/pgn]

Comments by Jeroen.