CCCC Lc0-Arasan : strange endgame

[ernest]

Lc0 is unable to win the obvious endgame, and suddenly (Black moves 144 and 145) Arasan stops fighting, and surrenders its 2 rooks !...

[pgn][Event "CCCC 1: Rapid Rumble (15|5) Stage 1"]
[Site "Chess.com"]
[Date "2018.09.06"]
[Round "?"]
[White "Lc0 17.11089"]
[Black "Arasan CCCC-2018"]
[Result "1-0"]
[WhiteElo "3300"]
[BlackElo "3179"]
[WhiteType "program"]
[BlackType "program"]
[ECO "D30"]
[Opening "Queen's gambit declined"]
[TimeControl "900+5"]
[Time "13:51:18"]
[Termination "normal"]
[PlyCount "293"]

1. d4 d5 2. c4 e6 3. Nf3 a6 4. cxd5 exd5 5. Nc3 Nc6 6. Qb3 Bb4 7. Bg5 Nge7 8. e3
f6 9. Bf4 Bg4 10. a3 Bxc3+ 11. Qxc3 g5 12. Bg3 h5 13. h3 Bxf3 14. gxf3 Nf5 15.
Bh2 Qd7 16. Be2 Nfe7 17. h4 gxh4 18. Bf1 Ng6 19. O-O-O O-O-O 20. b4 f5 21. a4
Qe7 22. b5 Qb4 23. Qxb4 Nxb4 24. Kd2 a5 25. Bh3 Ne7 26. Be5 Rh7 27. Rdg1 Rf8 28.
Rg5 Kd8 29. Rhg1 Rff7 30. Rc1 c6 31. b6 Na6 32. Bf1 Kc8 33. Bd6 Rh8 34. Bxe7
Rxe7 35. Rxf5 Kb8 36. f4 Rd7 37. Rg5 Rd6 38. Ke2 Rdd8 39. Kf3 Nb4 40. Kg2 h3+
41. Kxh3 h4 42. Rc5 Rhg8 43. Be2 Na2 44. Bd3 Rge8 45. Bb1 Nb4 46. Rxa5 Re7 47.
Rc5 Na6 48. Rc1 Ka8 49. Kxh4 Rf7 50. Kg4 Nb8 51. a5 Nd7 52. Bf5 Nf6+ 53. Kf3
Rff8 54. Bd3 Ne8 55. Rcg1 Nd6 56. Rg7 Nc4 57. Bxc4 dxc4 58. Rc1 Rd5 59. Rxc4
Rxa5 60. Rb4 Kb8 61. Rb1 Rc8 62. Rgg1 Rf8 63. Ke4 Ra2 64. Kf3 Re8 65. Rg7 Ra5
66. Rg5 Rd5 67. Re5 Red8 68. Ke4 R5d7 69. f5 Rf7 70. Ra1 Rdf8 71. Kf4 Kc8 72. e4
Kd7 73. Re6 Rh7 74. Ra7 Rb8 75. Ra1 Kd8 76. Rg1 Kd7 77. f3 Rf8 78. Reg6 Rh4+ 79.
Ke5 Rhh8 80. Rg7+ Kc8 81. Ra1 Kb8 82. Rg2 Re8+ 83. Kd6 Rd8+ 84. Ke5 Rhe8+ 85.
Kf4 Rd6 86. Ra4 c5 87. dxc5 Rf6 88. Rga2 Kc8 89. Rd2 Kb8 90. Rda2 Kc8 91. Rd4
Kb8 92. Rd3 Rc6 93. Rda3 Kc8 94. Rd2 Kb8 95. Ra5 Rf6 96. Ra1 Rc6 97. Rda2 Kc8
98. Rd1 Kb8 99. Rda1 Kc8 100. Rd2 Kb8 101. Rd3 Rxc5 102. Rda3 Kc8 103. Rd1 Kb8
104. Rda1 Kc8 105. Rd3 Kb8 106. Rad1 Kc8 107. Rd4 Rb5 108. Rd6 Rb3 109. Rc1+ Kb8
110. Rh1 Rc3 111. Rhd1 Kc8 112. R6d5 Rb3 113. Rd6 Rf8 114. Ra1 Kb8 115. Rh1 Rb4
116. Rdh6 Kc8 117. Rd6 Rc4 118. Ra1 Kb8 119. Rad1 Kc8 120. R6d3 Ra4 121. Rd6 Ra3
122. e5 Rc3 123. R6d4 Rc5 124. Ra4 Kb8 125. Rad4 Kc8 126. f6 Rc6 127. Kf5 Rxb6
128. f4 Rb5 129. Rd6 Kc7 130. Ke6 Rc5 131. R6d3 Re8+ 132. Kf5 Rf8 133. Rd4 Rh8
134. Rd7+ Kb6 135. R7d6+ Ka5 136. R6d2 b5 137. Rd7 b4 138. Rb7 Ka6 139. Rxb4 Ra5
140. Rdb1 Rh5+ 141. Ke6 Rh6 142. Kf5 Rh7 143. R4b3 Rf7 144. Ke6 Rd7 145. Kxd7
Rxe5 146. fxe5 Ka5 147. Ra3# 1-0[/pgn]

[Nay Lin Tun]

Morale, "Too much torture/troll ended up with Rage Quit!

[MikeGL]

I think nothing unusual on this game, just that Lc0 is again a pawn down but have a lot of pc activity for 1 pawn, and k activity in endgame.
Arasan probably saw a forced mate with or without giving up both his rooks.
The win for Lc0 is smooth, avoiding desperado rook tricks for a stalemate.

Lc0 is unable to win the obvious endgame, and suddenly (Black moves 144 and 145) Arasan stops fighting, and surrenders its 2 rooks !...

[pgn][Event "CCCC 1: Rapid Rumble (15|5) Stage 1"]
[Site "Chess.com"]
[Date "2018.09.06"]
[Round "?"]
[White "Lc0 17.11089"]
[Black "Arasan CCCC-2018"]
[Result "1-0"]
[WhiteElo "3300"]
[BlackElo "3179"]
[WhiteType "program"]
[BlackType "program"]
[ECO "D30"]
[Opening "Queen's gambit declined"]
[TimeControl "900+5"]
[Time "13:51:18"]
[Termination "normal"]
[PlyCount "293"]

1. d4 d5 2. c4 e6 3. Nf3 a6 4. cxd5 exd5 5. Nc3 Nc6 6. Qb3 Bb4 7. Bg5 Nge7 8. e3
f6 9. Bf4 Bg4 10. a3 Bxc3+ 11. Qxc3 g5 12. Bg3 h5 13. h3 Bxf3 14. gxf3 Nf5 15.
Bh2 Qd7 16. Be2 Nfe7 17. h4 gxh4 18. Bf1 Ng6 19. O-O-O O-O-O 20. b4 f5 21. a4
Qe7 22. b5 Qb4 23. Qxb4 Nxb4 24. Kd2 a5 25. Bh3 Ne7 26. Be5 Rh7 27. Rdg1 Rf8 28.
Rg5 Kd8 29. Rhg1 Rff7 30. Rc1 c6 31. b6 Na6 32. Bf1 Kc8 33. Bd6 Rh8 34. Bxe7
Rxe7 35. Rxf5 Kb8 36. f4 Rd7 37. Rg5 Rd6 38. Ke2 Rdd8 39. Kf3 Nb4 40. Kg2 h3+
41. Kxh3 h4 42. Rc5 Rhg8 43. Be2 Na2 44. Bd3 Rge8 45. Bb1 Nb4 46. Rxa5 Re7 47.
Rc5 Na6 48. Rc1 Ka8 49. Kxh4 Rf7 50. Kg4 Nb8 51. a5 Nd7 52. Bf5 Nf6+ 53. Kf3
Rff8 54. Bd3 Ne8 55. Rcg1 Nd6 56. Rg7 Nc4 57. Bxc4 dxc4 58. Rc1 Rd5 59. Rxc4
Rxa5 60. Rb4 Kb8 61. Rb1 Rc8 62. Rgg1 Rf8 63. Ke4 Ra2 64. Kf3 Re8 65. Rg7 Ra5
66. Rg5 Rd5 67. Re5 Red8 68. Ke4 R5d7 69. f5 Rf7 70. Ra1 Rdf8 71. Kf4 Kc8 72. e4
Kd7 73. Re6 Rh7 74. Ra7 Rb8 75. Ra1 Kd8 76. Rg1 Kd7 77. f3 Rf8 78. Reg6 Rh4+ 79.
Ke5 Rhh8 80. Rg7+ Kc8 81. Ra1 Kb8 82. Rg2 Re8+ 83. Kd6 Rd8+ 84. Ke5 Rhe8+ 85.
Kf4 Rd6 86. Ra4 c5 87. dxc5 Rf6 88. Rga2 Kc8 89. Rd2 Kb8 90. Rda2 Kc8 91. Rd4
Kb8 92. Rd3 Rc6 93. Rda3 Kc8 94. Rd2 Kb8 95. Ra5 Rf6 96. Ra1 Rc6 97. Rda2 Kc8
98. Rd1 Kb8 99. Rda1 Kc8 100. Rd2 Kb8 101. Rd3 Rxc5 102. Rda3 Kc8 103. Rd1 Kb8
104. Rda1 Kc8 105. Rd3 Kb8 106. Rad1 Kc8 107. Rd4 Rb5 108. Rd6 Rb3 109. Rc1+ Kb8
110. Rh1 Rc3 111. Rhd1 Kc8 112. R6d5 Rb3 113. Rd6 Rf8 114. Ra1 Kb8 115. Rh1 Rb4
116. Rdh6 Kc8 117. Rd6 Rc4 118. Ra1 Kb8 119. Rad1 Kc8 120. R6d3 Ra4 121. Rd6 Ra3
122. e5 Rc3 123. R6d4 Rc5 124. Ra4 Kb8 125. Rad4 Kc8 126. f6 Rc6 127. Kf5 Rxb6
128. f4 Rb5 129. Rd6 Kc7 130. Ke6 Rc5 131. R6d3 Re8+ 132. Kf5 Rf8 133. Rd4 Rh8
134. Rd7+ Kb6 135. R7d6+ Ka5 136. R6d2 b5 137. Rd7 b4 138. Rb7 Ka6 139. Rxb4 Ra5
140. Rdb1 Rh5+ 141. Ke6 Rh6 142. Kf5 Rh7 143. R4b3 Rf7 144. Ke6 Rd7 145. Kxd7
Rxe5 146. fxe5 Ka5 147. Ra3# 1-0[/pgn]

[jdart]

Yeah, I don't see any big error in the endgame. Black is just lost.

I was actually watching the first part of this game, and I think Arasan went wrong early in the opening. 8. .. f6 looks like an error. Arasan then expanded on the kingside with .. g5 and .. h5, but this was futile because White wound up castling queenside.

--Jon

[ernest]

Arasan probably saw a forced mate with or without giving up both his rooks.
The win for Lc0 is smooth, avoiding desperado rook tricks for a stalemate.

Hi Mike,

For Arasan, you may be right, I will ask Jon...

But I disagree when you say "the win for Lc0 is smooth", for about 40 moves Lc0 has no idea about how to win, eval is not advancing a bit, it's a dismal show (especially with Lc0 supposedly using Sygyzy). Comparing with the moves proposed by alpha-beta programs (e.g. Stockfish), you can see the big failings.
Maybe somebody from the Lc0 team can explain more.

[ernest]

Yeah, I don't see any big error in the endgame. Black is just lost.
--Jon

Hi Jon,

Indeed, Black is lost, but why does Arasan choose such a short death ?

(especially after resisting so well to the previous long series of Lc0's aimless moves...)

[frankp]

lc0 is not using tb in 4C.
The version playing is capable of only using WDL tables, but that makes the late endgame play super weird. The plan is to use both DTZ and WDL together once the code has been properly tested. In the next tournament, I guess, as changes to the engines are not allowed during or between rounds.

The endgame against arasan looked hysterical. At one time I thought lc0 was demonstrating how many ways you can arrange two rooks on an open a-file while not making any progress.
The endgame against Texel in a later game was impressive - rooks and pawns against bishop, knight and pawn. Curious.

lc0 games are rarely dull.

[jdart]

Indeed, Black is lost, but why does Arasan choose such a short death ?

(especially after resisting so well to the previous long series of Lc0's aimless moves...)

If you mean 144 .. Rd7, after a few seconds Arasan is getting a "TbLoss" score, indicating a certain loss (it starts hitting the 6-man tbs).

Arasan could have played so as to delay the mate further. But with Syzygy bases, you don't get a distance to mate score. So all it sees a tablebase loss, and one losing move is as good (or as bad) as another.

--Jon