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Up Topic The Rybka Lounge / Computer Chess / Lc0 can't find a TB loss for 24 moves; and a 'Pure' fail
- By MrKris (***) Date 2020-11-19 04:29
https://www.shredderchess.com/online/endgame-database.html
The Shredder online TB (Nalimov 6-pc.) has the below starting position as:

(shortest) "1.Qh4 win in 79 moves"
(2nd) "1.Qc2 win in 82", all other moves draw or lose.

Stockfish Syzygy-6 shows white as winning even with the default setting 'Syzygy50MoveRule' = ON because:
- the first phase, to win one of black's pawns, takes under 50 moves,
- the capture resets the count for the second phase, to win the Q vs R+pawn, which takes under 50 moves.

Stockfish was able to win without any Syzygy, which is what I wanted to test.
To test that I used the latest Lc0 with the latest net with Syzygy-6 ON.

To my surprise Lc0 could not find a tablebase win/loss -evaluation over +/- 100.- for the first 24 moves.
-- I checked each move manually at the Shredder site:
all of Lc0's moves with its Syzygy-6 should have had (bad for black here) -297 TB lost. like it finally had for  its 25...Rd8. [Event "G/5'+2''"]
[Site "R7 2700X 14ths | RTX 2060 | Ponder On"]
[Date "+/- for the mover, 2020.11.18"]
[Round "?"]
[White "Stockfish_20111513,SyzygyOFF"]
[Black "Lc0v0.26.3_J94-60,Syzygy-6"]
[Result "1-0"]
[FEN "8/5k2/4pp2/6r1/8/8/5Q2/5K2 w - - 0 1"]
[PlyCount "64"]
[SetUp "1"]
[Termination "adjudication"]
[TimeControl "300+2"]

1. Qh4 {+1.62/49 9.7s << ShredderChess 'Win in 79' <<} Kg7 {-0.66/9 5.2s} 2. Ke2 {+1.87/41 3.3s}
Rd5 {-0.79/11 7.1s} 3. Ke3 {+2.32/44 0s} Rg5 {-0.89/11 10s}
4. Kd4 {+2.81/48 7.1s} Rd5+ {-1.18/13 7.0s} 5. Kc4 {+2.90/50 4.1s}
Re5 {-1.64/17 6.7s} 6. Qh1 {+2.94/48 0.12s} Rd5 {-1.78/15 6.7s}
7. Qe4 {+3.03/56 9.9s} Re5 {-2.02/15 0.28s} 8. Qd3 {+3.03/51 4.7s}
Rd5 {-1.40/14 9.5s} 9. Qe4 {+3.12/55 0s} Re5 {-1.65/17 7.7s}
10. Qa8 {+3.12/55 0s} Kf7 {-1.56/16 8.7s} 11. Qh8 {+3.12/53 5.2s}
Kg6 {-2.02/17 5.6s} 12. Qg8+ {+3.21/49 0.92s} Kf5 {-2.14/17 3.0s}
13. Qh7+ {+3.22/53 2.5s} Kg5 {-1.82/17 10s} 14. Qg7+ {+3.23/53 0s}
Kf5 {-2.08/18 4.5s} 15. Qh6 {+3.48/51 22s} Rd5 {-3.77/20 0.25s}
16. Qh5+ {+3.64/47 6.3s} Kf4 {-1.81/15 18s} 17. Qh6+ {+4.30/39 7.8s}
Ke5 {-1.96/14 18s} 18. Qh2+ {+5.14/39 7.8s} Ke4 {-1.92/13 11s}
19. Qg2+ {+5.39/50 4.5s} Kf4 {-1.43/13 4.7s} 20. Qf2+ {+5.40/47 6.0s}
Kg5 {-1.56/14 5.7s} 21. Qe3+ {+5.65/39 5.7s} Kf5 {-1.99/18 0.29s}
22. Qe2 {+5.89/37 7.9s} Rd7 {-4.51/19 4.8s <<<< ShredderChess '(best) win in 56' <<<<}

( {Just for example, what black is trying to avoid:} 22. ... Re5 23. Qh5+ Kf4 24. Qh6+ Kf5 25. Kd3 Rd5+ 26. Ke3 Re5+ 27. Kf3 Rd5
28. Qh5# )

23. Qf3+ {+6.84/37 10s}
Ke5 {-5.30/14 0.21s} 24. Qe3+ {+6.92/47 8.6s} Kf5 {-3.21/17 14s}
25. Kc5 {+6.92/49 0.001s} Rd8 {-297.12/4 13s <<<< Finally!!} 26. Qh3+ {+7.00/48 0.001s}
Ke5 {-297.14/2 9.1s} 27. Qh2+ {+7.01/44 0s} Kf5 {-3.33/17 8.6s}
28. Qh7+ {+7.09/44 1.6s} Kg5 {-2.40/19 8.2s} 29. Qe7 {+7.09/46 0s}
Rd5+ {-3.34/18 4.2s} 30. Kc6 {+7.09/49 4.7s} Kf5 {-297.16/2 9.6s}
31. Qh7+ {+7.09/39 0s} Kf4 {-297.18/2 8.8s} 32. Qh6+ {+7.17/47 6.4s}
Ke5 {-297.20/2 8.4s, White wins by adjudication --I set the Resign setting better for the next two games to show the methods.} 1-0

Next Cfish (default Hybrid) with Syzygy = OFF was able to win vs. Stockfish with Syzygy-6 on.
Stockfish with Syzygy-6, of course, gave the correct evaluation, black is lost, from move 1... through the end.
After 52.Kxe6 the 50-move rule reset for a 2nd time, the first with 4...f5, showing how well Cfish played without Syzygy because it had to take a pawn before move 55.! [Event "G/5'+2''"]
[Site "R7 2700X"]
[Date "+/- for the mover, 2020.11.18"]
[Round "?"]
[White "Cfish-201024,SyzygyOFF"]
[Black "Stockfish_20111513,Syzygy-6"]
[Result "1-0"]
[FEN "8/5k2/4pp2/6r1/8/8/5Q2/5K2 w - - 0 1"]
[PlyCount "149"]
[SetUp "1"]
[TimeControl "300+2"]

1. Qh4 {+1.57/53 5.5s} Rf5+ {-152.65/45 13s} 2. Ke2 {+1.57/54 2.9s}
Kg6 {-152.65/47 6.2s} 3. Kd3 {+1.57/52 3.6s} Rd5+ {-152.65/47 4.3s}
4. Kc4 {+1.86/52 18s} f5 {-152.65/54 4.0s <<<< 50-move rule reset. <<<<} 5. Qh8 {+1.86/49 6.2s}
Kf7 {-152.65/56 4.0s} 6. Qh5+ {+1.86/50 3.9s} Kg7 {-152.65/51 4.6s}
7. Qh4 {+2.24/50 5.5s} Kg6 {-152.65/60 4.7s} 8. Qh8 {+2.24/53 3.9s}
Kf7 {-152.65/59 4.9s} 9. Qh7+ {+2.24/48 3.9s} Kf6 {-152.65/54 3.8s}
10. Qh1 {+2.24/61 4.9s} Kg7 {-152.65/52 4.8s} 11. Qe1 {+2.24/54 4.2s}
Kf6 {-152.65/53 5.7s} 12. Qe3 {+2.24/61 11s} Ke7 {-152.65/57 7.4s}
13. Qg5+ {+2.24/57 6.6s} Kf7 {-152.65/56 4.2s} 14. Qh6 {+2.24/55 4.3s}
Rd6 {-152.65/50 23s} 15. Qh7+ {+2.40/42 4.2s} Kf6 {-152.65/48 4.0s}
16. Qg8 {+2.49/46 4.4s} Rc6+ {-152.65/51 4.2s} 17. Kb5 {+2.75/50 5.8s}
Rc2 {-152.65/48 7.6s} 18. Qh8+ {+2.85/44 5.0s} Kf7 {-152.65/55 4.3s}
19. Qh7+ {+2.94/44 5.2s} Kf6 {-152.65/60 6.1s} 20. Qh4+ {+2.94/46 6.2s}
Kf7 {-152.65/53 9.5s} 21. Qh5+ {+3.18/47 17s} Ke7 {-152.65/54 7.3s}
22. Qh4+ {+3.18/49 5.2s} Kf7 {-152.65/57 4.4s} 23. Qd4 {+3.26/48 5.0s}
Rc1 {-152.65/57 4.3s} 24. Qd7+ {+3.63/48 17s} Kf6 {-152.65/56 19s}
25. Qd4+ {+3.72/40 3.5s} Kf7 {-152.65/55 4.6s} 26. Qd7+ {+3.79/39 4.4s}
Kf6 {-152.65/55 4.3s} 27. Qd2 {+3.85/40 4.3s} Rc8 {-152.65/57 8.8s}
28. Qd4+ {+4.09/40 6.0s} Ke7 {-152.65/55 9.7s} 29. Kb6 {+4.02/48 8.1s}
Rc2 {-152.65/51 7.3s} 30. Qg7+ {+4.35/44 20s} Kd6 {-152.65/48 6.6s}
31. Qd4+ {+4.47/38 3.8s} Ke7 {-152.65/35 0.77s} 32. Qd3 {+5.74/45 53s}
Rc8 {-152.65/45 15s} 33. Kb7 {+5.83/35 2.6s} Rg8 {-152.65/46 12s}
34. Kc7 {+5.99/37 3.9s} Rg4 {-152.65/50 26s} 35. Qc3 {+6.29/36 3.8s}
Rg2 {-152.65/47 14s} 36. Qb4+ {+6.70/39 4.3s} Kf7 {-152.65/45 6.1s}
37. Kd7 {+6.99/42 9.2s} Re2 {-152.65/47 6.4s} 38. Qc3 {+6.99/44 3.7s}
Re4 {-152.65/52 7.4s} 39. Kd6 {+7.07/44 9.0s} Re2 {-152.65/54 3.1s}
40. Kd7 {+7.47/43 32s} Re4 {-152.65/55 5.1s} 41. Qh8 {+7.59/44 8.6s}
Kg6 {-152.65/55 3.7s} 42. Ke7 {+7.63/41 2.9s} Kg5 {-152.65/56 3.2s}
43. Qh2 {+7.72/38 2.5s} Kg4 {-152.65/57 3.6s} 44. Qf2 {+7.80/40 3.0s}
Kh3 {-152.65/39 24s} 45. Qg1 {+9.00/36 6.0s} Re5 {-152.65/41 16s}
46. Qd4 {+14.47/36 8.6s} Re4 {-152.65/35 2.2s} 47. Qf2 {+17.57/31 6.8s}
Kg4 {-152.65/40 11s} 48. Kf6 {+19.11/29 1.5s} Kh3 {-152.65/39 8.5s}
49. Qg1 {+43.44/29 1.9s} Kh4 {-152.65/46 6.3s} 50. Qg2 {+44.96/31 2.3s}
Ra4 {-152.65/44 1.9s} 51. Qh1+ {+46.25/32 2.1s} Kg3 {-152.65/33 2.5s}
52. Kxe6 {+47.88/32 2.1s <<<< 50-move rule reset. <<<<} Rf4 {-152.65/41 9.9s} 53. Ke5 {+53.13/33 2.0s}
Rf2 {-298.58/40 6.7s} 54. Qg1+ {+60.32/34 2.1s} Kf3 {-152.65/31 0.40s}
55. Kxf5 {+62.04/32 2.0s} Rd2 {-M52/45 2.5s} 56. Qg4+ {+M63/36 2.5s}
Kf2 {-M48/46 0.38s} 57. Qc4 {+M37/48 3.1s} Ke1 {-M60/39 0.51s}
58. Ke4 {+M35/45 5.8s} Kf2 {-M36/48 0.79s} 59. Kf4 {+M33/44 3.8s}
Re2 {-M32/60 0.89s} 60. Qd4+ {+M31/47 8.1s} Ke1 {-M30/58 1.1s}
61. Qg1+ {+M29/44 9.1s} Kd2 {-M28/57 0.60s} 62. Kf3 {+M27/48 1.1s}
Re1 {-M26/59 1.3s} 63. Qf2+ {+M25/45 0.61s} Kd1 {-M24/64 1.5s}
64. Qb2 {+M23/46 5.3s} Re8 {-M22/69 1.1s} 65. Qb5 {+M21/44 2.2s}
Re1 {-M20/75 1.4s} 66. Kf2 {+M19/45 1.8s} Re7 {-M18/83 1.6s}
67. Qd3+ {+M17/52 1.6s} Kc1 {-M16/90 1.2s} 68. Qa3+ {+M15/61 0.32s}
Kc2 {-M14/97 1.9s} 69. Qxe7 {+M13/76 0.80s} Kb3 {-M12/233 1.3s}
70. Qe4 {+M11/169 0.51s} Kc3 {-M10/245 0.35s} 71. Ke3 {+M9/245 0.39s}
Kb3 {-M8/245 0.018s} 72. Kd3 {+M7/245 0.017s} Ka2 {-M6/245 0.008s}
73. Qb4 {+M5/245 0.017s} Ka1 {-M4/245 0.005s} 74. Kc2 {+M3/245 0.005s}
Ka2 {-M2/245 0.003s} 75. Qb2# {+M1/245 0.004s, White mates} 1-0

Disappointingly Cfish set to 'Pure' --no other changes from the above-- failed to find the win.
With Cfish's 34.Qe8 Shredder.com says 'win in 70',
but Stockfish with its 34...Kd6 said -0.49 draw range!, realizing white had taken too long since the last pawn move/capture 7...f5,
that is white would not be able to take a pawn, resetting the rule, before move 58.
Then with its 44.Qb8 Cfish-Pure said 0.00 draw, realizing that also although without Szygy. [Event "G/5'+2''"]
[Site "R7 2700X"]
[Date "+/- for the mover, 2020.11.18"]
[Round "?"]
[White "Cfish-201024-Pure,SyzygyOFF"]
[Black "Stockfish_20111513,Syzygy-6"]
[Result "1/2-1/2"]
[FEN "8/5k2/4pp2/6r1/8/8/5Q2/5K2 w - - 0 1"]
[PlyCount "109"]
[SetUp "1"]
[TimeControl "300+2"]

1. Qh4 {+0.69/45 25s} Kg6 {-152.65/57 27s} 2. Kf2 {+0.69/50 2.9s}
Re5 {-152.65/49 1.9s} 3. Qg4+ {+0.69/49 3.7s} Kf7 {-152.65/53 3.0s}
4. Qc4 {+0.69/49 3.8s} Rd5 {-152.65/47 3.3s} 5. Ke3 {+0.69/45 4.2s}
Re5+ {-152.65/53 6.1s} 6. Kd4 {+0.69/48 3.5s} Rd5+ {-152.65/54 4.2s}
7. Kc3 {+0.69/50 3.4s} f5 {-152.65/47 9.2s} 8. Qc7+ {+0.69/52 13s}
Kg6 {-152.65/52 7.4s} 9. Kc4 {+0.69/48 7.6s} Rd1 {-152.65/56 4.9s}
10. Qg3+ {+0.69/49 3.4s} Kf7 {-152.65/55 20s} 11. Qh2 {+0.69/46 4.4s}
Rc1+ {-152.65/50 4.7s} 12. Kd3 {+0.69/45 6.9s} Rc8 {-152.65/52 7.8s}
13. Kd4 {+0.69/50 4.0s} Rc6 {-152.65/53 14s} 14. Qh7+ {+0.69/48 4.9s}
Kf6 {-152.65/50 4.3s} 15. Qh1 {+0.69/52 6.4s} Ra6 {-152.65/55 3.9s}
16. Qh6+ {+0.69/46 4.7s} Kf7 {-152.65/55 4.0s} 17. Kc5 {+0.69/54 6.2s}
Ra5+ {-152.65/58 4.2s} 18. Kb4 {+0.69/51 6.0s} Rd5 {-152.65/56 12s}
19. Kc3 {+0.69/51 7.2s} Rc5+ {-152.65/58 4.0s} 20. Kb4 {+0.69/52 8.1s}
Rd5 {-152.65/60 4.3s} 21. Kc4 {+0.69/49 4.7s} Rd6 {-152.65/47 11s}
22. Qh5+ {+0.69/53 4.4s} Ke7 {-152.65/49 4.1s} 23. Qg6 {+0.69/40 8.0s}
Rd5 {-152.65/53 4.2s} 24. Qg8 {+0.69/49 6.4s} Kd7 {-152.65/49 4.1s}
25. Qf7+ {+0.69/50 9.5s} Kd6 {-152.65/51 4.4s} 26. Qb7 {+0.69/50 5.8s}
Ke5 {-152.65/53 4.1s} 27. Qb8+ {+0.69/52 9.0s} Kf6 {-152.65/53 4.3s}
28. Qf8+ {+0.69/52 5.9s} Ke5 {-152.65/52 7.4s} 29. Qh8+ {+0.69/55 23s}
Kd6 {-152.65/46 9.8s} 30. Qd8+ {+0.69/44 5.6s} Kc6 {-152.65/47 5.1s}
31. Qf8 {+0.69/49 4.8s} Kd7 {-152.65/54 9.6s} 32. Qh8 {+0.69/46 4.3s}
Kc7 {-152.65/56 4.3s} 33. Qh5 {+0.69/49 12s} Kc6 {-152.65/52 4.8s}
34. Qe8+ {+0.69/44 4.6s} Kd6 {-0.49/58 6.1s} 35. Qf8+ {+0.69/43 4.2s}
Kc6 {-0.49/50 5.2s} 36. Qb8 {+0.69/44 4.1s} Kd7 {-0.47/44 27s}
37. Qb4 {+0.69/41 4.1s} Kc6 {-0.47/57 4.6s} 38. Qe7 {+0.69/49 3.8s}
Re5 {-0.47/56 4.8s} 39. Qe8+ {+0.69/46 18s} Kc7 {-0.47/57 23s}
40. Qh8 {+0.69/39 4.9s} Rd5 {-0.43/27 3.8s} 41. Qg8 {+0.69/41 11s}
Kd7 {-0.43/28 3.6s} 42. Qf7+ {+0.61/32 3.5s} Kd6 {-0.43/26 12s}
43. Qf8+ {+0.69/40 6.4s} Kc6 {-0.41/24 8.3s} 44. Qb8 {0.00/34 33s}
Kd7 {-0.39/23 2.7s} 45. Qa7+ {0.00/40 6.2s} Kc6 {-0.39/46 4.3s}
46. Kc3 {0.00/37 4.3s} Kd6 {-0.37/37 2.9s} 47. Qa3+ {0.00/40 4.5s}
Kd7 {-0.35/36 3.3s} 48. Qa7+ {0.00/40 6.1s} Kd6 {-0.35/36 3.1s}
49. Kc4 {0.00/41 2.0s} Kc6 {-0.35/52 4.0s} 50. Qa8+ {0.00/56 17s}
Kd7 {-0.33/40 4.3s} 51. Qxd5+ {0.00/71 1.9s} exd5+ {0.00/82 2.9s}
52. Kxd5 {0.00/81 2.4s} f4 {0.00/89 9.7s} 53. Ke4 {0.00/87 6.1s}
f3 {0.00/105 32s} 54. Ke3 {0.00/91 2.5s} f2 {0.00/66 0.81s}
55. Kxf2 {0.00/84 2.2s, Draw by insufficient mating material} 1/2-1/2
Up Topic The Rybka Lounge / Computer Chess / Lc0 can't find a TB loss for 24 moves; and a 'Pure' fail

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