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Up Topic The Rybka Lounge / Computer Chess / A Brilliant Ending Lesson by Lc0 (but it lost)
- By MrKris (***) Date 2021-04-03 18:29 Upvotes 1
(From an experiment by me that is in progress.
Thanks to https://www.shredderchess.com/online/endgame-database.html .)


Lightning G/90"+1", neither with Syzygy,
Lc0 only with a 10x128 net gives a lesson about Q+2 pawns vs. Q endings.

The first part of the game is important only to show that:
1) Lc0's seeming too near zero evaluations are probably closer to the actual than they appear;
2) Stockfish's evaluations are not yet too high, showing a pawn up chances but little more;
although for both the complexity makes an exact determination difficult.
[Event "G/90''+1'' 1GBh noSyzygy"]
[Site "R7 2700X | RTX 2060"]
[Date "2021.04.01"]
[Round "1"]
[White "Lc0-0.27+_J104.1-30"]
[Black "Stockfish_21032717_4ths"]
[Result "0-1"]
[BlackElo "2400"]
[ECO "B01"]
[Opening "Scandinavian"]
[Variation "Schiller, 4.d4 Nf6"]
[WhiteElo "2400"]
[TimeControl "90+1"]
[Termination "normal"]
[PlyCount "243"]
[WhiteType "human"]
[BlackType "human"]

1. e4 {book} d5 {book} 2. exd5 {book} Qxd5 {book} 3. Nc3 {book} Qd6 {book}
4. d4 {+0.24/14 0 8.6s} Nf6 {-0.70/29 0 6.9s} 5. Nf3 {+0.24/16 0 0.21s} c6
{-0.84/27 0 1.9s} 6. Ne5 {+0.24/16 0 0.56s} Nbd7 {-0.72/25 0 1.4s} 7. Nc4
{+0.24/15 0 2.0s} Qc7 {-0.50/24 0 1.4s} 8. a4 {+0.26/14 0 1.8s} Nb6
{-0.53/27 0 1.7s} 9. Ne5 {+0.26/13 0 1.1s} Bf5 {-0.61/28 0 8.8s} 10. a5
{+0.28/16 0 3.4s} Nbd7 {-0.67/26 0 1.7s} 11. Bf4 {+0.29/16 0 0.61s} Nxe5
{-0.94/27 0 2.4s} 12. Bxe5 {+0.28/16 0 0.56s} Qd7 {-0.81/28 0 1.7s} 13. Bd3
{+0.27/14 0 4.4s} Ng4 {-0.54/25 0 1.6s} 14. Bg3 {+0.27/14 0 1.0s} Bxd3
{-0.59/27 0 2.3s} 15. Qxd3 {+0.25/13 0 0.72s} e6 {-0.60/28 0 1.5s} 16. h3
{+0.26/13 0 3.2s} Nh6 {-0.54/26 0 2.0s} 17. Be5 {+0.24/13 0 4.1s} f6
{-0.38/24 0 1.8s} 18. Bh2 {+0.22/15 0 3.3s} Be7 {-0.28/27 0 2.3s} 19. Ne2
{+0.29/10 0 3.3s} Rd8 {-0.23/24 0 1.8s} 20. O-O {+0.26/12 0 4.2s} Nf5
{-0.33/27 0 3.6s} 21. c3 {+0.27/13 0 0.21s} O-O {-0.43/27 0 3.8s} 22. Rfe1
{+0.27/11 0 2.1s} Rfe8 {-0.34/26 0 1.1s} 23. Qc2 {+0.26/12 0 3.0s} Bf8
{-0.39/28 0 5.0s} 24. Rad1 {+0.27/10 0 2.9s} Nh4 {-0.32/27 0 1.4s} 25. b4
{+0.27/11 0 1.4s} b6 {-0.37/27 0 1.7s} 26. a6 {+0.25/11 0 4.0s} Nf5
{-0.55/27 0 11s} 27. Nf4 {+0.23/11 0 2.8s} Bd6 {-0.37/26 0 1.3s} 28. Nh5
{+0.24/12 0 0.62s} Bxh2+ {-0.47/25 0 1.9s} 29. Kxh2 {+0.22/12 0 0.80s} Ne7
{-0.55/26 0 2.2s} 30. Re4 {+0.22/11 0 2.5s} f5 {-0.46/28 0 10s} 31. Re2
{+0.29/12 0 2.3s} Ng6 {-0.39/22 0 1.0s} 32. Rde1 {+0.28/10 0 1.4s} Qd5
{-0.24/29 0 5.7s} 33. Qc1 {+0.31/13 0 2.3s} c5 {-0.26/25 0 0.97s} 34. dxc5
{+0.30/16 0 0.83s} bxc5 {-0.24/26 0 1.4s} 35. b5 {+0.30/12 0 0.37s} e5
{-0.17/26 0 2.0s} 36. c4 {+0.18/13 0 7.9s} Qd6 {-0.12/23 0 1.5s} 37. f3
{+0.18/18 0 0.20s} h6 {0.0032 1.3s} 38. Qb2 {+0.06/12 0 4.6s} e4+ {+0.84/22
0 1.5s} 39. Kh1 {-0.08/13 0 2.5s} Re5 {+0.31/26 0 3.9s} 40. Qb3 {-0.07/15 0
2.1s} Qe7 {+0.41/27 0 2.8s} 41. f4 {-0.08/14 0 2.9s} Re6 {+0.52/25 0 1.9s}
42. Rd1 {-0.08/17 0 0.42s} Red6 {+0.30/35 0 12s} 43. Rxd6 {-0.01/12 0 1.2s}
Rxd6 {+0.35/35 0 3.1s} 44. Qb2 {-0.06/13 0 2.4s} Rd1+ {+0.79/21 0 0.63s}
45. Kh2 {-0.11/13 0 0.77s} Qc7 {+0.35/26 0 1.8s} 46. Rf2 {-0.11/11 0 0.21s}
Kh7 {+0.32/23 0 0.67s} 47. Qc3 {-0.09/11 0 1.0s} Rd3 {+0.37/23 0 0.95s} 48.
Qb2 {-0.08/11 0 2.4s} Qf7 {+0.21/28 0 3.9s} 49. Qa1 {-0.12/21 0 3.0s} Nh4
{+0.78/21 0 0.37s} 50. Ng3 {-0.13/29 0 0.20s} Qg6 {+0.42/29 0 2.1s} 51. Nf1
{-0.07/19 0 1.7s} Qe6 {+0.46/28 0 0.35s} 52. Qb1 {-0.10/19 0 0.48s} Qxc4
{+0.93/24 0 0.47s} 53. b6 {-0.09/21 0 1.7s} axb6 {+1.08/24 0 0.44s} 54. Qa2
{-0.07/20 0 0.20s} Qd4 {+0.92/26 0 0.83s} 55. Re2 {-0.45/19 0 3.6s} (55. a7
{? Sf -1.91} Ra3 56. Rd2 Rxa2 57. Rxa2 Qc4 58. a8=Q Qxf1 {wh R vs. bk
Nppp}) 55. .. Qd8 {+1.06/25 0 0.69s} 56. a7 {-0.49/20 0 0.20s} Qa8
{+0.98/22 0 0.50s} 57. Ne3 {-0.48/19 0 0.61s} Rd7 {+1.10/24 0 0.64s} 58.
Nxf5 {-0.43/18 0 3.3s} Rxa7 {+1.02/26 0 1.0s} 59. Qe6 {-0.44/16 0 0.20s}
Ng6 {+0.89/26 0 0.73s} 60. Rxe4 {-0.45/18 0 0.21s} b5 {+1.31/30 0 4.3s} 61.
Ng3 {-0.61/18 0 3.3s} Re7 {+0.90/26 0 0.65s} 62. Qf5 {-0.62/22 0 0.20s} Qb7
{+0.96/28 0 0.53s} 63. Rxe7 {-0.72/24 0 1.7s ----This is Lc0's peak disadvantage, until its ?? later.} Here is Lc0's brilliant lesson:
1) Stockfish evaluation goes up as it is making exchanges an winnig a second pawn, and its typical 'plateau' of +(for black)2.11 is from move 73 through 97 with a few slightly above/below through 109 - if black can win this it would have to make more progress in the game, Stockfish seems content with high evaluations instead of actual win-ability with a material advantage;
(After the game though Stockfish fairly quickly goes down to +(for black)1.22 but is 'stuck' high in the game for tens of moves.)
2) Meanwhile Lc0's evaluation show a declining disadvantage (closer to zero) - declining to the extent, again at lightning with a small net and nether having Syzygy, that at 80.Nxf4 after the recapture it shows -0.25 in a tablebase drawn position after its 80.Nxf4!!
[FEN "8/1q2R1pk/6np/1pp2Q2/5P2/6NP/6PK/8 b - - 0 63"]

63. .. Qxe7 {+1.41/26 0 0.59s Stockfish's evaluation goes over 1.00 (+ for black) for the first time?} 64. Ne4 {-0.68/25 0 0.21s} c4 {+0.94/27 0 1.3s} 65. g3 {-0.66/24 0 0.20s} b4
{+1.08/27 0 0.52s} 66. h4 {-0.66/21 0 0.54s} Qf8 {+1.65/26 0 0.49s} 67. Qb5
{-0.65/21 0 0.52s} c3 {+1.41/26 0 0.84s} 68. h5 {-0.61/23 0 1.2s} Ne7
{+1.32/28 0 0.61s} 69. Qxb4 {-0.62/23 0 0.21s} c2 {+1.79/30 0 0.68s} 70.
Qc4 {-0.61/21 0 0.21s} Qc8 {+2.02/30 0 1.1s} 71. Nc5 {-0.60/20 0 0.49s} Qf5
{+1.86/27 0 0.92s} 72. g4 {-0.59/19 0 0.49s} Qxg4 {+1.97/30 0 0.54s} 73.
Qxc2+ {-0.58/18 0 0.86s} Kh8 {+2.12/32 0 0.62s} 74. Nd3 {-0.56/18 0 0.76s}
Nd5 {+2.11/37 0 0.64s} 75. Qg2 {-0.35/16 0 3.8s} Qxh5+ {+2.11/36 0 0.75s}
76. Qh3 {-0.35/1 0 0s} Qe2+ {+2.11/39 0 0.75s} 77. Kg1 {-0.35/14 0 0.21s}
Qd1+ {+2.11/41 0 0.81s} 78. Kf2 {-0.29/14 0 4.2s} Qd2+ {+2.11/43 0 0.84s}
79. Kg1 {-0.29/1 0 0s} Nxf4 {?? +2.11/43 0 1.8s >>>>Only ? if there is no way to win, in either case this makes a 6-piece tablebase DRAW, Stockfish's evaluation is decisively -wrong result- bad!!} 80. Nxf4 {!! Best and drawing. -0.25/12 0 1.7s} ({(If} 80.Qf3 {?? the only alternative} Ng6 {!! Stockfish takes 3 minutes to get up to +(for black)6.00; it difficult to be certain but black has the possibility of making more progress than in the game before allowing a 6-piece ending.}) Instead of 110.Qh8+?? losing, Lc0 still had 3 moves to stay in a tablebase DRAW: 110.Qf2/Qf1/Qb4, all other moves are tablebase losses.
[FEN "7k/6p1/7p/8/5N2/7Q/3q4/6K1 b - - 0 80"]
80... Qxf4 {+2.11/45 0 0.77s ?? for Sf's evaluation.} 81. Qd3 {-0.24/1 0 0.001s >>>>Tablebase DRAW with Lc0 at its ending MINIMUM evalution, Stockfish in its HIGH PLATEAU! -before the later ??-} Kg8 {+2.11/41 0 0.74s} 82. Kg2 {-0.24/12 0 0.73s} Qg4+ {+2.11/38 0 0.78s} 83. Kh2
{-0.22/11 0 1.2s} Qh5+ {+2.12/41 0 2.0s} 84. Kg2 {-0.21/9 0 1.2s} Qg5+
{+2.12/41 0 0.44s} 85. Kh3 {-0.20/9 0 0.73s} Qh5+ {+2.11/41 0 1.2s} 86. Kg2
{-0.18/10 0 0.89s} Qe5 {+2.11/43 0 1.0s} 87. Qb3+ {-0.20/9 0 0.77s} Kf8
{+2.11/43 0 1.4s} 88. Qb7 {-0.19/8 0 0.27s} h5 {+2.11/36 0 0.58s} 89. Qd7
{-0.23/9 0 2.0s} Kg8 {+2.11/41 0 1.0s} 90. Qd3 {-0.28/9 0 0.56s} Kf7
{+2.11/41 0 0.65s} 91. Kh1 {-0.27/10 0 0.46s} Qe1+ {+2.11/37 0 0.76s} 92.
Kh2 {-0.26/11 0 2.1s} Qe5+ {+2.11/40 0 0.84s} 93. Kh3 {-0.31/13 0 3.3s} Kf6
{+2.11/42 0 0.71s} 94. Qd8+ {-0.32/1 0 0s} Kg6 {+2.11/42 0 0.74s} 95. Qd1
{-0.31/11 0 0.42s} Qe3+ {+2.11/39 0 0.75s} 96. Kg2 {-0.45/14 0 2.0s} Qg5+
{+2.11/40 0 0.93s} 97. Kh3 {-0.33/11 0 0.65s} Qf5+ {+2.11/41 0 0.95s} 98.
Kh2 {-0.51/15 0 1.2s} Qf4+ {+2.19/42 0 1.3s} 99. Kh3 {-0.52/16 0 0.20s} h4
{+2.19/42 0 0.94s} 100. Kg2 {-0.50/15 0 0.21s} Kg5 {+2.03/40 0 4.1s} 101.
Qd5+ {-0.44/12 0 0.89s} Qf5 {+2.19/37 0 0.37s} 102. Qd8+ {-0.34/13 0 0.75s}
Kh5 {+2.03/38 0 0.81s} 103. Qh8+ {-0.34/15 0 0.63s} Kg6 {+2.03/39 0 0.58s}
104. Qe8+ {-0.35/15 0 0.20s} Kh6 {+2.03/39 0 0.70s} 105. Qh8+ {-0.37/13 0
0.25s} Qh7 {+2.11/42 0 1.8s} 106. Qf8 {-0.38/14 0 0.79s} Qg6+ {+2.03/35 0
1.1s} 107. Kh2 {-0.49/16 0 2.4s} Qg3+ {+2.03/35 0 0.63s} 108. Kh1 {-0.39/1
0 0s} Qe1+ {+2.11/38 0 1.8s} 109. Kg2 {-0.45/14 0 2.0s} Qe5 {+2.03/36 0
0.68s} 110. Qh8+ {-0.52/15 0 1.5s ?? Shredderchess.com Nalimov 'lose in
35'} ({Only 3 moves draw, ALL others lose.} 110. Qf2 {=}) (110. Qf1 {=})
(110. Qb4 {=}) 110. .. Kg6 {+6.92/23 0 0.64s} 111. Qa8 {-0.49/16 0 0.21s}
(111. Qxh4 Qg5+ {M24} 112. Kh3 Qxh4+ 113. Kxh4 Kf5) 111. .. Qg3+ {+7.50/23
0 0.64s} 112. Kh1 {-0.42/13 0 0.96s} Qh3+ {+8.71/23 0 0.63s} 113. Kg1
{-0.31/1 0 0s} Qg4+ {+9.09/22 0 0.77s} 114. Kf2 {-3.24/15 0 1.5s} h3
{+9.31/23 0 0.73s} 115. Qe8+ {-5.01/18 0 19s} Kh7 {+9.97/24 0 0.75s} 116.
Qe5 {-5.06/1 0 0s} Qg2+ {+11.03/24 0 1.3s} 117. Ke3 {-4.74/1 0 0.031s} Kh6
{+11.40/22 0 0.69s} 118. Qb8 {-4.99/1 0 0.090s} Qg5+ {+12.73/22 0 0.86s}
119. Kf2 {-5.90/14 0 4.0s} Kh7 {+56.69/33 0 0.76s} 120. Qh2 {-6.95/17 0
8.0s} Qd2+ {+60.22/43 0 1.8s} 121. Kg3 {-7.43/1 0 0s} Qxh2+ {+60.22/44 0
3.1s} 122. Kxh2 {-7.17/18 0 0.17s, Black wins by adjudication} 0-1

If the N's are exchanged here is an example of what it takes for a black win, compare this to above after 80...Qxf4:
Kh2 lose in 44; Kh1 lose in 34; Kf1 lose in 15; Qf2 lose in 13.
--DRAW if the black K is on g7
then Kh1/h2=; Kf1-+ in 16; Qf2-+ in 14.--
8/8/6k1/7p/3q2p1/8/6Q1/6K1 w - - 0 1


The screenshot shows Stockfish's +2.11(for it, black) evaluation and depth in the game.
6-piece DRAW moves 80 through 109:
Attachment: post-3apr2021.pgn - The game in 'one piece'. (7k)
Up Topic The Rybka Lounge / Computer Chess / A Brilliant Ending Lesson by Lc0 (but it lost)

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