An infinity of source code words

Leela Chess Zero – Stockfish

Top Chess Engine Championship Season 15 – Superfinal; match game 12; tcec-chess.com, May 12, 2019

French Defence C05

Leela Chess Zero and Stockfish do not want to say goodbye, so they engaged themselves in another 100-game match. 1. e4 e6 2. d4 d5 3. Nd2 Nf6 4. e5 Nfd7 5. f4 c5 6. c3 Nc6 7. Ndf3 Qb6 8. g3 Be7 9. Kf2 a5 10. a4 cxd4 11. cxd4 Ndb8 12. Ne2 0-0 13. Kg2 Na6 14. Nc3 f6 15. h4 fxe5 16. dxe5 h6 17. Bd3 Nab4 18. Bb1 Bd7 19. Na2 Rac8 20. Kh3 Be8 21. Nxb4 Nxb4 22. Ra3 Bc5 23. Bd2 Qa6 24. Rc3 b5 25. Qc1 Qb6 26. Nd4 bxa4 27. Be3 Bd7 28. Nf5 Bxe3 29. Ne7+ Kf7 30. Nxc8 Rxc8 31. Qxe3 d4 32. Qf2 Qb7 33. Rcc1 d3 34. h5 Rxc1 35. Rxc1 Qd5 36. Kh4 Bc6 37. g4 Ke8 38. Rf1 Qd8+ 39. Kg3 Qd5 40. Rd1 Qb3 41. Rd2 Qc4 42. Rd1 Qb3 43. Qd2 Be4 44. Re1 Bb7 45. Rd1 Be4 46. Kh4 Qd5 47. Qc3 Kf7 48. Qc7+ Kg8 49. Qc3 Kh7 50. Kh3 Kg8 51. Kh4 Kh7 52. Kg3 Kg8 53. Qc8+ Kh7 54. Qc1 Qb3 55. Qd2 Kg8 56. g5 Kf8 57. g6 Ke7 58. Kh3 Ke8 59. Kh4 Qc4 60. Kg3 Bf5 61. Qc3 Qxc3 62. bxc3 Nc2 63. Kf2 a3 64. Ba2 Kd7 65. Bb3 Kc7 66. Rg1 Kd7

Black has only a Pawn for the Exchange, but two passers (potentially three) are more than enough compensation. Now White should content itself with a draw as follows: 67. Rd1 Kc7 68. Bc4 a4 69. Ba2 Kc6 70. Rg1 Kc7 71. Rd1 Kc6 repeating moves. 67. Kf3? This instead proves to be an unusual and fatal mistake, even though Stockfish’s refutation is very elegant: 67. ... d2! 68. Ke2 Ne1 69. Kd1 Nf3. The inconsiderate 69. ... Bc2+?? 70. Kxd2 Nf3+ 71. Kxc2 Nxg1 would lead only to a draw. 70. Rh1 Bd3! 71. Ba4+ Ke7 72. Bb3 Bb1! 73. Rh3 Be4 74. Rh1 Nxe5 75. Rf1 a4! 76. Ba2. Or 76. Bxa4 a2 71. Kxd2 Nc4+ 72. Ke2 Bb1 and game over. 76. ... Nf3 77. Rh1 Bd3 78. Rh3 Bf5! 79. Rh1 Kd6 80. Bc4 Bb1 81. Rh3 0 : 1. There might have followed 81. ... Be4 82. Rh1 Nd4! 83. Rh2 Nb3! winning easily.

Kasia Derwinska, Alice Chess. Photo courtesy of Isabella Garrucho Fine Art/Artnet.