====== Chess - Programming - Evaluation - Tests ======

===== The famous Bg5 move in the AZ-SF8 game of 2017 =====

Move 21 is amazing.  Try to see if my engine gets this too.

<code>
[Event "AlphaZero - Stockfish"]
[Site "London ENG"]
[Date "2017.12.04"]
[EventDate "?"]
[Round "?"]
[Result "1-0"]
[White "AlphaZero (Computer)"]
[Black "Stockfish (Computer)"]
[ECO "E17"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "233"]

1. d4 Nf6 2. c4 e6 3. Nf3 b6 4. g3 Bb7 5. Bg2 Be7 6. O-O O-O
7. d5 exd5 8. Nh4 c6 9. cxd5 Nxd5 10. Nf5 Nc7 11. e4 Bf6
12. Nd6 Ba6 13. Re1 Ne8 14. e5 Nxd6 15. exf6 Qxf6 16. Nc3 Nb7
17. Ne4 Qg6 18. h4 h6 19. h5 Qh7 20. Qg4 Kh8 21. Bg5 f5
22. Qf4 Nc5 23. Be7 Nd3 24. Qd6 Nxe1 25. Rxe1 fxe4 26. Bxe4
Rf5 27. Bh4 Bc4 28. g4 Rd5 29. Bxd5 Bxd5 30. Re8+ Bg8 31. Bg3
c5 32. Qd5 d6 33. Qxa8 Nd7 34. Qe4 Nf6 35. Qxh7+ Kxh7 36. Re7
Nxg4 37. Rxa7 Nf6 38. Bxd6 Be6 39. Be5 Nd7 40. Bc3 g6 41. Bd2
gxh5 42. a3 Kg6 43. Bf4 Kf5 44. Bc7 h4 45. Ra8 h5 46. Rh8 Kg6
47. Rd8 Kf7 48. f3 Bf5 49. Bh2 h3 50. Rh8 Kg6 51. Re8 Kf7
52. Re1 Be6 53. Bc7 b5 54. Kh2 Kf6 55. Re3 Ke7 56. Re4 Kf7
57. Bd6 Kf6 58. Kg3 Kf7 59. Kf2 Bf5 60. Re1 Kg6 61. Kg1 c4
62. Kh2 h4 63. Be7 Nb6 64. Bxh4 Na4 65. Re2 Nc5 66. Re5 Nb3
67. Rd5 Be6 68. Rd6 Kf5 69. Be1 Ke5 70. Rb6 Bd7 71. Kg3 Nc1
72. Rh6 Kd5 73. Bc3 Bf5 74. Rh5 Ke6 75. Kf2 Nd3+ 76. Kg1 Nf4
77. Rh6+ Ke7 78. Kh2 Nd5 79. Kg3 Be6 80. Rh5 Ke8 81. Re5 Kf7
82. Bd2 Ne7 83. Bb4 Nd5 84. Bc3 Ke7 85. Bd2 Kf6 86. f4 Ne7
87. Rxb5 Nf5+ 88. Kh2 Ke7 89. Ra5 Nh4 90. Bb4+ Kf7 91. Rh5
Nf3+ 92. Kg3 Kg6 93. Rh8 Nd4 94. Bc3 Nf5+ 95. Kxh3 Bd7 96. Kh2
Kf7 97. Rb8 Ke6 98. Kg1 Bc6 99. Rb6 Kd5 100. Kf2 Bd7 101. Ke1
Ke4 102. Bd2 Kd5 103. Rf6 Nd6 104. Rh6 Nf5 105. Rh8 Ke4
106. Rh7 Bc8 107. Rc7 Ba6 108. Rc6 Bb5 109. Rc5 Bd7 110. Rxc4+
Kd5 111. Rc7 Kd6 112. Rc3 Ke6 113. Rc5 Nd4 114. Be3 Nf5
115. Bf2 Nd6 116. Rc3 Ne4 117. Rd3 1-0
</code>

<WRAP info>
**NOTE:**  AlphaZero (Computer) vs Stockfish (Computer)

  * AlphaZero - Stockfish (2017), London ENG, Dec-04
  * Queen's Indian Defense: Classical Variation. Polugayevsky Gambit (E17)  ·  1-0 


  * Lc0 v0.26 + SV-4300 default setting find 21.Bg5!! at depth 22, ~3M nodes, eval +1.21
  * Stockfish12 dev 20071720, default setting do not find the move at depth 48, 1.6T nodes.
  * SF NNUE 090720, default setting do not find the move at depth 42, 0.77T nodes. 

  * SF11    - N/A after 30 minutes of thinking (~20,000,000 nps)
  * SFNN    - 0 minutes 12 seconds (~13,000,000 nps)
  * Lc0-T60 - 7 minutes 2 seconds (~8500 nps)

Interestingly SFNN thinks it's winning even before it sees Bg5!! It thinks b4! is +3 before finding Bg5!! at +4.5

SEE:  https://www.chessgames.com/perl/chessgame?gid=1899418

</WRAP>