What's up with this endgame?

zullil · Post by **zullil** » Sun Jul 21, 2019 12:30 pm

Eelco de Groot wrote: ↑Sun Jul 21, 2019 12:07 pm Now Kaissa seems to get stuck a little here Louis... Assuming I entered the line correctly into Uly's pgn so far. Could it be a tablebase thing? But 63...Be4 seems just a wrong move...
[d]8/5B2/2k2p2/K2p2p1/3P1P2/3bP1P1/8/8 b - -

Hi Eelco,

Here's what I get. My search has been running for more than 12 hours, with a 32 GB hash table and 6-man tables:

+8.29 63... Bf1 64. Be8+ Kc7 65. Bb5 Bh3 66. Be2 Kc6 67. Bd3 Bg4 68. Bg6 Be2 69. Be8+ Kc7 70. Ba4 Kb7 71. Bd7 Kc7 72. Be6 Kd6 73. Bg8 Bh5 74. Ka6 Be8 75. Kb6 Bg6 76. Kb7 Bf5 77. Bf7 Bh3 78. Bg6 Be6 79. Bd3 Bd7 80. Kb8 Be8 81. Bh7 Ba4 82. Bf5 Bc6 83. fxg5 fxg5 84. Kc8 Ba4 85. Kd8 Bc6 86. Bd3 Ba4 87. Bg6 Bd7 88. Bc2 Bg4 89. Bd3 Bd7 90. Ba6 g4 91. Bd3 Kc6 92. Be2 Kd6 93. Bd1 Bf5 94. Ba4 Bd3 95. Bd7 Bh7 96. Bxg4 Kc6 97. Bd7+ Kb6 (depth 60, 0:08:52)

+8.29 63... Be2 64. Be8+ Kc7 65. Ba4 Kb7 66. Bd7 Kc7 67. Be6 Kd6 68. Bg8 Bh5 69. Ka6 Be8 70. Kb6 Bg6 71. Kb7 Bf5 72. Bf7 Bh3 73. Kb6 Bf5 74. Be8 Bc8 75. Bg6 Bg4 76. Bd3 Bh5 77. Bb5 Bd1 78. Be8 Bc2 79. Kb7 Bf5 80. Kb8 Bh3 81. Bh5 Kc6 82. Bf3 Bf5 83. Be2 Bh3 84. Ba6 Bf5 85. Bb7+ Kd6 86. Bc8 Be4 87. Bg4 Bb1 88. Kb7 Bg6 89. Ka7 Kc7 90. Bf3 gxf4 91. exf4 Be4 92. Be2 Bc2 93. Ka6 Kc6 94. Bh5 Bf5 95. Be8+ Kc7 96. Kb5 Kd6 97. Bh5 Bd3+ 98. Kb6 Ke6 (depth 60, 0:08:52)

+8.29 63... Be4 64. Be8+ Kd6 65. Kb6 Bg2 66. Bf7 Bf3 67. Bg6 Bg4 68. Bd3 Bd7 69. Bh7 Bh3 70. Bc2 Bg4 71. Bb3 Bh3 72. Ba4 Bf1 73. Bc6 Bg2 74. Be8 Be4 75. Bh5 Bg2 76. Bg4 Be4 77. Bc8 Bg6 78. Kb7 Be8 79. fxg5 fxg5 80. Bg4 Bb5 81. Kb6 Bc4 82. Bc8 Bb3 83. Kb7 Ba4 84. Bf5 Bb3 85. Bg4 Ba2 86. Bc8 Bb1 87. Bh3 Bd3 88. Kc8 Ba6+ 89. Kd8 Bb7 90. Ke8 Bc6+ 91. Kf7 Kc7 92. Be6 Kd6 93. Kf6 Ba8 94. Bf7 Bc6 95. Kxg5 Ke7 96. Bg8 Kf8 97. Be6 Ke7 98. Bf5 (depth 60, 0:08:52)

Louis

Vinvin · Post by **Vinvin** » Sun Jul 21, 2019 3:39 pm

Eelco de Groot wrote: ↑Sun Jul 21, 2019 12:07 pm Or is it just because you disabled nullmove in CFish? That I can believe, if it is some sort of Zugzwang and Stockfish also would not see it on time..

Null move is surely an issue in endgames where both side only 1 bishop of same color (+pawns) because zugzwang is often a way to win.
A club mate showed me a year ago a game he lost with such a material and he told me Stockfish overlooked the win.
IMHO, developers should remove null move in KB vs KB (+pawns) with bishop of same color in their engine !

Paloma · Post by **Paloma** » Sun Jul 21, 2019 4:31 pm

Ovyron wrote: ↑Sat Jul 20, 2019 8:44 am I just lost my first ICCF game since 2015, and I still don't know what happened.

At the end of 2017 I reached this endgame:

Congrats, close to four Years without any defeat.

In which tournament on the ICCF did you play this game? You were black?

Ovyron · Post by **Ovyron** » Sun Jul 21, 2019 4:45 pm

zullil wrote: ↑Sun Jul 21, 2019 11:36 am [d]8/3b2k1/1p3pp1/3p1p2/3P1P2/P3P3/5KP1/5B2 b - - 0 40

+7.52 40... g5 41. Ke1 Kf8 42. Kd2 Ke7 43. Kc3 Be8 44. Kb4 Kd8 45. Bb5 Bh5 46. Bc6 Bf7 47. Kb5 Kc7 48. g3 Bg8 49. Be8 Kd8 50. Bg6 Kc7 51. Bh5 Be6 52. Kb4 Bc8 53. Be2 Bd7 54. a4 Be8 55. Bb5 Bg6 56. a5 bxa5+ 57. Kxa5 Bh5 58. Bd3 Kc6 59. Bc2 Be2 60. Bxf5 Bf3 61. Be6 Be2 62. Bg8 Bd3 63. Bf7 Be4 64. Be8+ Kc7 65. Kb5 Kd6 66. Bf7 Bd3+ 67. Kb6 gxf4 68. gxf4 Bf1 69. Bg6 Bh3 70. Kb7 Bg4 71. Bd3 Be6 72. Bb5 Bh3 73. Kb6 Bf5 74. Bc6 Be4 75. Be8 Ke7 76. Bb5 Kd6 77. Bc6 Bh1 78. Be8 Be4 79. Kb7 Bd3 80. Bf7 f5 81. Be8 Bf1 82. Kb6 Be2 83. Bc6 Bd1 84. Bb5 Bc2 85. Kb7 Bd1 86. Kc8 (depth 78, 8:57:10)

Looks like White wins.

Thanks, that looks very definite! So let's see if I can make Stockfish 9 Learn learn the true score of the position...

Initial run:

60/08 4:13 +0.15 40...Kf7 41.Ke1 Ke6 42.Kd2 Ba4 43.Bd3 Kd6 44.Kc3 (663.480.488) 2614 TB:912.448
60/05 4:13 +0.15 40...Ba4 41.Ke1 Kf7 42.Kd2 Ke6 (663.480.488) 2614 TB:912.448
60/13 4:13 +0.15 40...Kf8 41.Ke1 Ke7 42.Bd3 Kd6 43.Kd2 Bc6 44.Kc3 Ba4 45.Kb4 Bd1 46.Kb5 Kc7 (663.480.488) 2614 TB:912.448
60/30 4:13 +0.45 40...Be6 41.Bd3 Kf7 42.Ke1 Ke7 43.Kd2 Kd6 44.Kc3 Bd7 45.Kb3 Kc7 46.Be2 Be8 47.Kb4 Kd6 48.Bb5 Bf7 49.Bd3 Be8 50.a4 Bf7 51.a5 bxa5+ 52.Kxa5 Be6 53.Kb6 Bg8 (663.480.488) 2614 TB:912.448

No wonder I lost the game, I allowed this position because it looked like a draw! The challenge was to not allow it on the first place...

After 40...Kf7:

[d]8/3b1k2/1p3pp1/3p1p2/3P1P2/P3P3/5KP1/5B2 w - -

60/03 3:04 +0.32 41.Ke1 Ba4 42.g3 (489.523.348) 2649 TB:897.054
60/03 3:04 +0.32 41.Bd3 Ba4 42.Ke1 (489.523.348) 2649 TB:897.054
60/10 3:04 +0.32 41.Be2 Ba4 42.Ke1 Bc2 43.Kd2 Be4 44.g3 Ke7 45.Kc3 Kd6 (489.523.348) 2649 TB:897.054
60/03 3:04 +0.32 41.g3 Ba4 42.Ke1 (489.523.348) 2649 TB:897.054

Okay, just 7.20 off the mark...

41.Ke1

[d]8/3b1k2/1p3pp1/3p1p2/3P1P2/P3P3/6P1/4KB2 b - -

60/51 2:54 +0.21 41...Ke7 42.Kd2 Ba4 43.Kc3 Kd7 44.Bd3 Kd6 45.Kb4 Bd1 46.Kb5 Kc7 47.a4 Kd6 48.Kxb6 Bxa4 49.Ka5 Bb3 50.Kb5 Bd1 51.Kb4 Kc6 52.Bb5+ Kb6 53.Be8 g5 54.Kc3 Be2 (492.644.715) 2815 TB:1.076.057
60/07 2:54 +0.21 41...Ke6 42.Bd3 Kd6 43.Kd2 Ba4 44.Kc3 Kc7 (492.644.715) 2815 TB:1.076.057
60/03 2:54 +0.21 41...Ba4 42.Bd3 Ke6 (492.644.715) 2815 TB:1.076.057
60/03 2:54 +0.21 41...Ke8 42.Bd3 Ke7 (492.644.715) 2815 TB:1.076.057

41...Ke7

[d]8/3bk3/1p3pp1/3p1p2/3P1P2/P3P3/6P1/4KB2 w - -

60/03 3:17 +0.21 42.Kf2 Ba4 43.Bd3 (499.413.662) 2534 TB:986.007
60/27 3:17 +0.21 42.Bd3 Kd6 43.Kf2 Be8 44.Ke2 Kc7 45.Kd2 Bc6 46.Kc3 Ba4 47.Kb4 Bd1 48.Kb5 Bb3 49.g3 Bd1 50.Kb4 Bg4 51.Bb5 Bf3 52.Be8 g5 53.Kc3 Kd6 54.Bg6 Be4 55.Bf7 (499.413.662) 2534 TB:986.007
60/04 3:17 +0.21 42.Kd2 Kd6 43.g3 Ba4 (499.413.662) 2534 TB:986.007
60/18 3:17 +0.21 42.Be2 Kd6 43.Bd3 Be8 44.Kd2 Bc6 45.Kc3 Ba4 46.Kb4 Bd1 47.Bb5 Bc2 48.Be8 g5 49.Kb5 Kc7 50.Bf7 Be4 (499.413.662) 2534 TB:986.007

As long as it doesn't see it, its moves seem random...

42.Kd2

[d]8/3bk3/1p3pp1/3p1p2/3P1P2/P3P3/3K2P1/5B2 b - -

60/03 2:21 +0.30 42...Ba4 43.Bd3 Kd6 (447.792.593) 3156 TB:754.381
60/06 2:21 +0.30 42...Kd8 43.Kc3 Ba4 44.Bd3 Kc7 45.Kb4 (447.792.593) 3156 TB:754.381
60/03 2:21 +0.30 42...Kd6 43.Kc3 Ba4 (447.792.593) 3156 TB:754.381
60/66 2:21 +0.48 42...Ke6 43.Kc3 Be8 44.Kb4 Kd6 45.Bb5 Bf7 46.a4 Kc7 47.Bd3 Kd6 48.a5 bxa5+ 49.Kxa5 Kc6 50.Ba6 Kc7 51.Kb5 Kd6 52.Kb6 Be6 53.Bb5 Bf7 54.Ba4 Be6 55.Be8 g5 (447.792.593) 3156 TB:754.381

42...Ba4

[d]8/4k3/1p3pp1/3p1p2/b2P1P2/P3P3/3K2P1/5B2 w - -

60/04 3:11 +0.22 43.Bd3 Kd6 44.Kc3 Kc7 (602.459.596) 3150 TB:1.768.979
60/03 3:11 +0.22 43.Kc3 Kd7 44.Bd3 (602.459.596) 3150 TB:1.768.979
60/03 3:11 +0.22 43.Ba6 Kd7 44.Kc3 (602.459.596) 3150 TB:1.768.979
60/03 3:11 +0.22 43.Be2 Kd6 44.Kc3 (602.459.596) 3150 TB:1.768.979

43.Kc3

[d]8/4k3/1p3pp1/3p1p2/b2P1P2/P1K1P3/6P1/5B2 b - -

60/11 1:59 +0.39 43...Kd6 44.Bd3 Ke7 45.Kb4 Be8 46.Bc2 Kd6 47.Bb3 Ke6 48.g3 Kd6 (446.207.148) 3745 TB:659.384
60/05 1:59 +0.39 43...Kd7 44.Bd3 Kd6 45.Kb4 Be8 (446.207.148) 3745 TB:659.384
60/06 1:59 +0.39 43...Kd8 44.Ba6 Kc7 45.Bd3 Kd6 46.Kb4 (446.207.148) 3745 TB:659.384
60/34 1:59 +0.39 43...Be8 44.Kb4 Kd6 45.Bb5 Bf7 46.Bd3 Be6 47.a4 Bf7 48.a5 bxa5+ 49.Kxa5 Kc6 50.Bb5+ Kc7 51.Ba6 Kc6 52.Be2 Bg8 53.Bb5+ Kd6 54.Be8 g5 55.Kb4 Be6 56.Bb5 Bf7 (446.207.148) 3745 TB:659.384

43...Kd6

[d]8/8/1p1k1pp1/3p1p2/b2P1P2/P1K1P3/6P1/5B2 w - -

60/18 3:16 +0.30 44.g3 Bd1 45.Bb5 Bf3 46.Bd3 Kc6 47.Kb4 Kb7 48.Bb5 Be4 49.Be8 g5 50.Bf7 Kc7 51.Kc3 Kd6 52.Be8 Ke6 (526.453.380) 2673 TB:1.712.373
60/03 3:16 +0.30 44.Bd3 Kc7 45.Kb4 (526.453.380) 2673 TB:1.712.373
60/03 3:16 +0.30 44.Kb4 Bd1 45.Kc3 (526.453.380) 2673 TB:1.712.373
60/04 3:16 +0.30 44.Ba6 Kc6 45.Kb4 Bc2 (526.453.380) 2673 TB:1.712.373

44.Kb4

[d]8/8/1p1k1pp1/3p1p2/bK1P1P2/P3P3/6P1/5B2 b - -

60/03 6:24 +0.30 44...Bc2 45.g3 Kc7 (994.598.164) 2586 TB:2.699.834
60/31 6:24 +0.30 44...Bd1 45.Bd3 Kc7 46.g3 Kd6 (994.598.164) 2586 TB:2.699.834
60/17 6:24 +0.31 44...Be8 45.Bb5 Bf7 46.Kc3 Kc7 47.Kb3 Kd6 48.Kb4 Kc7 49.Be2 Kc6 50.g3 Kc7 51.Bf1 Be6 52.Bb5 Bf7 (994.598.164) 2586 TB:2.699.834
60/67 6:24 +1.45 44...Bd7 45.Bb5 Bc8 46.Be8 Ba6 47.Bxg6 Bf1 48.g3 Bh3 49.Kb5 Kc7 50.Bf7 Bf1+ 51.Kb4 Kd6 52.Be8 Bd3 53.Bg6 Bc2 54.Kb5 Kc7 55.Bh7 Bd3+ 56.Ka4 Kc6 57.Kb4 Be4 (994.598.164) 2586 TB:2.699.834

44...Bc2

[d]8/8/1p1k1pp1/3p1p2/1K1P1P2/P3P3/2b3P1/5B2 w - -

60/03 0:51 +0.30 45.g3 Be4 46.Be2 (230.465.813) 4465 TB:391.423
60/04 0:51 +0.30 45.Be2 Be4 46.g3 Kc6 (230.465.813) 4465 TB:391.423
60/06 0:51 +0.30 45.Bb5 Be4 46.g3 Kc7 47.Be8 g5 (230.465.813) 4465 TB:391.423
60/25 0:51 +0.30 45.Kb5 Kc7 46.Be2 Be4 47.g3 Bc2 48.Kb4 Be4 49.Kc3 g5 50.Kb4 Kc6 51.Bb5+ Kd6 52.Bf1 Kc7 53.Kb5 Kb7 54.Ka4 Kc6 55.Bb5+ Kc7 56.Be8 Bd3 57.Bh5 (230.465.813) 4465 TB:391.423

45.Bb5

[d]8/8/1p1k1pp1/1B1p1p2/1K1P1P2/P3P3/2b3P1/8 b - -

60/05 1:34 +0.30 45...g5 46.Be8 Be4 47.g3 Kc7 (328.722.237) 3465 TB:566.717
60/17 1:34 +0.30 45...Bb1 46.Be8 g5 47.g3 Kc7 48.Bf7 Be4 49.Kb3 Kc6 50.Kc3 Kc7 51.Be8 Kd6 52.Bb5 Kc7 53.Kb4 Kd6 (328.722.237) 3465 TB:566.717
60/03 1:34 +0.30 45...Be4 46.g3 g5 (328.722.237) 3465 TB:566.717
60/03 1:34 +0.30 45...Kc7 46.Be8 g5 (328.722.237) 3465 TB:566.717

45...g5

Interesting, with the King on d6 white's 46.Bc6 is not possible. But supposedly white's best defense has the king on d8. So here's where I switch to single-PV to see if Stockfish sees the light...

[d]8/8/1p1k1p2/1B1p1pp1/1K1P1P2/P3P3/2b3P1/8 w - -

60/39 0:32 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (152.583.893) 4765 TB:369.645
60/39 0:32 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (152.583.930) 4765 TB:369.645
61/39 0:34 +0.19 46.g3 Be4 (164.781.276) 4773 TB:394.655
61/39 0:34 +0.19 46.g3 Be4 (164.781.320) 4773 TB:394.655
62/39 0:35 +0.19 46.g3 Be4 (170.036.277) 4772 TB:404.106
62/39 0:35 +0.19 46.g3 Be4 (170.036.327) 4772 TB:404.106
63/39 0:42 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (203.741.532) 4746 TB:477.179
63/39 0:42 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (203.741.593) 4746 TB:477.179
64/39 0:48 +0.19 46.g3 Be4 47.Be2 (228.799.514) 4760 TB:537.618
64/39 0:48 +0.19 46.g3 Be4 47.Be2 (228.799.706) 4760 TB:537.618
65/39 0:57 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 (275.086.297) 4754 TB:673.302
65/39 0:57 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 (275.086.336) 4754 TB:673.302
66/39 1:13 +0.19 46.g3 Be4 (346.466.501) 4719 TB:918.568
66/39 1:13 +0.19 46.g3 Be4 (346.466.525) 4719 TB:918.568
67/39 1:17 +0.19 46.g3 Be4 47.Be2 Kc7 (367.210.394) 4726 TB:970.054
67/39 1:17 +0.19 46.g3 Be4 47.Be2 Kc7 (367.210.421) 4726 TB:970.054
68/39 1:36 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 52.Kb5 Kc7 53.Be8 (454.547.203) 4704 TB:1.225.605
68/39 1:36 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 52.Kb5 Kc7 53.Be8 (454.547.573) 4704 TB:1.225.607
69/39 2:05 +0.19 46.g3 Be4 (546.126.984) 4356 TB:1.585.595
69/39 2:05 +0.19 46.g3 Be4 (546.127.084) 4356 TB:1.585.595
70/39 2:14 +0.19 46.g3 Be4 (571.431.164) 4236 TB:1.681.932
70/39 2:14 +0.19 46.g3 Be4 (571.431.180) 4236 TB:1.681.934
71/39 2:48 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 (663.518.961) 3929 TB:2.099.471
71/39 2:48 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 (663.518.961) 3929 TB:2.099.471
72/39 3:48 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (827.054.299) 3619 TB:2.827.297
72/39 3:48 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (827.054.299) 3619 TB:2.827.297
73/39 4:14 +0.19 46.g3 Be4 (893.892.396) 3508 TB:3.112.727
73/39 4:14 +0.19 46.g3 Be4 (893.892.410) 3508 TB:3.112.727
74/39 4:35 +0.19 46.g3 Be4 (942.726.301) 3418 TB:3.347.362
74/39 4:35 +0.19 46.g3 Be4 (942.726.301) 3418 TB:3.347.362
75/39 6:27 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 (1.229.991.710) 3176 TB:5.065.327
75/39 6:27 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 (1.229.991.737) 3176 TB:5.065.327
76/39 7:29 +0.19 46.g3 Be4 47.Be2 (1.399.371.255) 3116 TB:5.760.491
76/39 7:29 +0.19 46.g3 Be4 47.Be2 (1.399.371.280) 3116 TB:5.760.491
77/39 10:31 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 (1.854.081.227) 2935 TB:9.792.864
77/39 10:31 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 (1.854.081.255) 2935 TB:9.792.864
78/39 11:01 +0.19 46.g3 Be4 (1.931.488.732) 2918 TB:10.652.538
78/39 11:01 +0.19 46.g3 Be4 (1.931.488.754) 2918 TB:10.652.538
79/39 13:47 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (2.344.552.310) 2832 TB:14.364.936
79/39 13:47 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (2.344.552.557) 2832 TB:14.364.936
80/39 15:54 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 52.Kb5 Kc7 (2.671.073.972) 2798 TB:16.704.831
80/39 15:54 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 52.Kb5 Kc7 (2.671.074.011) 2798 TB:16.704.831
81/39 20:06 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (3.284.738.466) 2722 TB:21.906.952
81/39 20:06 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (3.284.738.471) 2722 TB:21.906.952
82/39 21:38 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (3.517.404.781) 2708 TB:23.694.648
82/39 21:38 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (3.517.404.815) 2708 TB:23.694.648
83/39 25:12 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 (4.059.325.707) 2683 TB:26.747.997
83/39 25:12 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 (4.059.325.707) 2683 TB:26.747.997
84/39 29:13 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 (4.616.262.150) 2632 TB:30.546.589
84/39 29:13 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 (4.616.262.208) 2632 TB:30.546.591
85/39 32:53 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (5.170.108.626) 2619 TB:33.920.405
85/39 32:53 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ (5.170.108.626) 2619 TB:33.920.405
86/39 37:45 +0.19 46.g3 Be4 (5.887.933.596) 2598 TB:40.104.800
86/39 37:45 +0.19 46.g3 Be4 (5.887.933.623) 2598 TB:40.104.800
87/39 39:45 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 (6.174.467.494) 2588 TB:42.691.988
87/39 39:45 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 (6.174.467.550) 2588 TB:42.691.988
88/39 55:37 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 52.Kb5 Kc7 53.Be8 Bd3+ 54.Kb4 Be4 55.Kc3 Kd6 56.Bb5 Kc7 57.Kb3 Kd6 58.Kb4 Ke7 59.Be2 (8.718.632.430) 2612 TB:67.866.757
88/39 55:37 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 52.Kb5 Kc7 53.Be8 Bd3+ 54.Kb4 Be4 55.Kc3 Kd6 56.Bb5 Kc7 57.Kb3 Kd6 58.Kb4 Ke7 59.Be2 (8.718.632.467) 2612 TB:67.866.757
89/39 56:05 +0.19 46.g3 Be4 47.Be2 Kc7 48.Kb5 Bc2 49.Bh5 Bd3+ 50.Kb4 Kd6 51.Bg6 Be4 52.Kb5 Kc7 53.Be8 Bd3+ 54.Kb4 Be4 55.Kc3 Kd6 56.Bb5 Kc7 57.Kb3 Kd6 58.Kb4 Ke7 59.Be2 (8.789.766.012) 2611 TB:68.507.563

Nothing after depth 88. Did I just blunder white's win? I can't believe despite knowing the position is won, I can't find the winning moves

Looks like Learning is useless here...

Paloma wrote: ↑Sun Jul 21, 2019 4:31 pmCongrats, close to four Years without any defeat.

Thanks, though that's just on the ICCF, I had already lost a game in the LSS (chess-server.net) where competition looks a lot more fierce than any other place, like FICGS.

Paloma wrote: ↑Sun Jul 21, 2019 4:31 pmIn which tournament on the ICCF did you play this game? You were black?

Yeah, I was black. No tourney, this was part of the friendly match México-Perú 2017 (this was the last game, so it finished a few days ago). We played this endgame for more than a year...

Zenmastur · Post by **Zenmastur** » Sun Jul 21, 2019 5:34 pm

Ovyron wrote: ↑Sat Jul 20, 2019 8:44 am I just lost my first ICCF game since 2015, and I still don't know what happened.

At the end of 2017 I reached this endgame:

[d]8/3b2k1/1p3pp1/3p1p2/3P1P2/P3P3/5KP1/5B2 b - -

I analyzed it thoroughly and concluded it was an easy draw, as I couldn't find any progress for white. There were positions where Stockfish showed 0.00 up to depth 60. There were positions where Stockfish wouldn't show any progress up to depth 80 o_O

Note that my opponent had what I believed were more advantageous positions before, and he abandoned them for this endgame, which makes me believe he knew it was winning, which means this position is a white to move and mate in N.

I guess my analysis was done with engines that are now very updated, but I'd still like to know what's going on.

Full Pgn:

[pgn]1. d4 d5 2. Bf4 c5 3. c3 Nf6 4. e3 e6 5. Nd2 Nc6 6. Ngf3 Nh5 7. Bg5 f6 8. Bh4 g6 9. Be2 Ng7 10. Bg3 cxd4 11. cxd4 Nf5 12. O-O Kf7 13. a3 h5 14. Nh4 Nxg3 15. hxg3 Kg7 16. f4 Bd7 17. Nb3 b6 18. Bd3 Ne7 19. Rc1 Be8 20. g4 Rc8 21. Qf3 hxg4 22. Qxg4 Rh6 23. Nd2 Bd7 24. Qg3 Qe8 25. Ndf3 Nf5 26. Nxf5+ exf5 27. Rxc8 Qxc8 28. Qe1 Bd6 29. Kf2 b5 30. Qa5 Qb7 31. Rc1 Rh8 32. Bf1 Qb6 33. Qxb6 axb6 34. Ne1 b4 35. axb4 Ra8 36. Rc3 Ra1 37. Ra3 Rxe1 38. Kxe1 Bxb4+ 39. Kf2 Bxa3 40. bxa3 Ba4 41. Ke1 Kf7 42. Kd2 Ke7 43. Kc3 Kd6 44. Bd3 Kc7 45. Kb4 Bd1 46. Kb5 Bg4 47. Ka6 Bd1 48. Bb5 Bc2 49. Be8 Bd3+ 50. Ka7 g5 51. g3 Be2 52. Ba4 Bd3 53. Bb3 gxf4 54. exf4 Be4 55. Ba4 Bf3 56. Ka6 Be2+ 57. Bb5 Bg4 58. Bd3 Bh3 59. Kb5 Kb7 60. a4 Kc7 61. a5 bxa5 62. Kxa5 Kc6 63. Bb5+ Kc7 64. Ka6 Bg2 65. Be8 Bf1+ 66. Ka5 Bd3 67. Bg6 Bc2 68. Kb5 Kd6 69. Bh5 Bd3+ 70. Kb6 Bb1 71. Kb7 Be4 72. Kc8 Ke7 73. Kc7 Bd3 74. Kc6 Ke6 75. Be8 Bb1 76. Kc5 Be4 77. Bb5 Bh1 78. Ba6 Be4 79. Bb7 Kd7 80. Bxd5 Bc2 81. Bf7 Bd1 82. Bc4 Bf3 83. Bd3 Be4 84. Kc4 {Black Resigns. 1-0} [/pgn]

Well,

[d]8/3b2k1/1p1b1pp1/3p1p2/1P1P1P2/R3P3/1P3KP1/r3NB2 b - - 4 37

Code: Select all

( [Stockfish 120719 64 BMI2] 51:+2.27 37...Rxa3 38.bxa3 Ba4 ([Stockfish 120719 64 BMI2] 51:+3.32) 39.Bd3 Kf7 40.Nf3 Be8
  41.Nd2 Ke7 42.Nb1 Bf7 43.Nc3 Kd7 44.Ke2 Be7 45.Bb5+ Kc7 46.Kd2 Bf8 47.Bd3 Bh6 48.Kc2 Bf8 49.Na4 Be6 50.Kb3 Be7 51.Nc3
   Bd8 52.Bb5 Bf7 53.Be2 Kd6 54.Kc2 Be6 55.Bd3 Be7 56.a4 Kc6 57.Bb5+ Kb7 58.Kb3 Bf7 59.Ka3 Bd8 60.Na2 Be7 61.Kb2 Bd6 
   62.Kb3 Bc7 63.Be2 Bd8 64.Bd3 Be8 65.Nc3 Bf7 )

Not great...

[d]8/3b2k1/1p3pp1/3p1p2/1b1P1P2/R3P3/1P4P1/4KB2 w - - 0 39

Code: Select all

( [Stockfish 120719 64 BMI2] 47:+5.73  39.Kd1 Kf7 40.Ra6 Ba5 41.Ra7 Ke6 42.Bd3 Be8 43.Ke2 Bd7 44.Bc2 Kd6 45.Rb7 Ke6 
 46.Kf3 Bc6 47.Rg7 Be8 48.Bb3 Bd2 49.Rb7 Ba5 50.Rb8 Bb5 51.Bc2 Bd7 52.Rh8 Ke7 53.Bb3 Be6 54.Rh7+ Kd8 55.Rb7 Ke8 56.Rb8+ 
 Ke7 57.Ke2 Kd6 58.Ba4 b5 59.Bxb5 g5 60.Rb7 Bc8 61.Ra7 Bb6 62.Ra8 Be6 63.Kd3 Kc7 64.Rf8 Kd6 65.Rxf6 gxf4 66.exf4 Ke7 
 67.Rh6 )
( [Stockfish 120719 64 BMI2] 63:+5.20 39.Kd1 Bxa3 40.bxa3 Be8 41.Kc2 Kf7 42.Kc3 Ke6 43.Kb4 g5 44.a4 Kd6 45.a5 Kc7 46.a6
 Kb8 47.Bb5 Bh5 48.Bd3 Bg6 49.Kb5 Kc7 50.g3 Be8+ 51.Kb4 Bd7 52.fxg5 fxg5 53.Bb5 Bc8 54.a7 Bb7 55.Be2 Bc6 56.Ba6 Ba8 
 57.Kb3 Kc6 58.Kc3 Kc7 59.Kd2 Bc6 60.Kd1 Kd6 61.Kc1 Ke7 62.Kb2 Kd6 63.Kc3 Kc7 64.Kd2 Kd6 65.Bc8 b5 66.Bxf5 Kc7 67.Ke2 
 b4 68.Kf3 b3 69.Kg4 b2 70.Kxg5 Kb7 71.g4 Bd7 72.Bb1 Be6 73.Kf4 Bg8 74.g5 Kxa7 75.Ke5 Ka6 76.Kd6 Kb5 77.e4 dxe4 78.Bxe4
  Bb3 79.g6 Kc4 80.Ke5 Kc3 81.g7 Bf7 82.d5 )

He let you off the hook by not playing 39.Kd1!

[pgn]1.d4 d5 2.Bf4 c5 3.c3 Nf6 4.e3 e6 5.Nd2 Nc6 6.Ngf3 Nh5 7.Bg5 f6 8.Bh4 g6 9.Be2 Ng7 10.Bg3 cxd4 11.cxd4 Nf5 12.O-O Kf7 13.a3 h5 14.Nh4 Nxg3 15.hxg3 Kg7 16.f4 Bd7 17.Nb3 b6 18.Bd3 Ne7 19.Rc1 Be8 20.g4 Rc8 21.Qf3 hxg4 22.Qxg4 Rh6 23.Nd2 Bd7 24.Qg3 Qe8 25.Ndf3 Nf5 26.Nxf5+ exf5 27.Rxc8 Qxc8 28.Qe1 Bd6 29.Kf2 b5 30.Qa5 Qb7 31.Rc1 Rh8 32.Bf1 Qb6 33.Qxb6 axb6 34.Ne1 b4 35.axb4 Ra8 36.Rc3 Ra1 37.Ra3 Rxe1 ( 37...Rxa3 38.bxa3 Ba4 39.Bd3 Kf7 40.Nf3 Be8 41.Nd2 Ke7 42.Nb1 Bf7 43.Nc3 Kd7 44.Ke2 Be7 45.Bb5+ Kc7 46.Kd2 Bf8 47.Bd3 Bh6 48.Kc2 Bf8 49.Na4 Be6 50.Kb3 Be7 51.Nc3 Bd8 52.Bb5 Bf7 53.Be2 Kd6 54.Kc2 Be6 55.Bd3 Be7 56.a4 Kc6 57.Bb5+ Kb7 58.Kb3 Bf7 59.Ka3 Bd8 60.Na2 Be7 61.Kb2 Bd6 62.Kb3 Bc7 63.Be2 Bd8 64.Bd3 Be8 65.Nc3 Bf7 ) 38.Kxe1 Bxb4+ 39.Kf2 ( 39.Kd1 Kf7 40.Ra6 Ba5 41.Ra7 Ke6 42.Bd3 Be8 43.Ke2 Bd7 44.Bc2 Kd6 45.Rb7 Ke6 46.Kf3 Bc6 47.Rg7 Be8 48.Bb3 Bd2 49.Rb7 Ba5 50.Rb8 Bb5 51.Bc2 Bd7 52.Rh8 Ke7 53.Bb3 Be6 54.Rh7+ Kd8 55.Rb7 Ke8 56.Rb8+ Ke7 57.Ke2 Kd6 58.Ba4 b5 59.Bxb5 g5 60.Rb7 Bc8 61.Ra7 Bb6 62.Ra8 Be6 63.Kd3 Kc7 64.Rf8 Kd6 65.Rxf6 gxf4 66.exf4 Ke7 67.Rh6 ) ( 39.Kd1 Bxa3 40.bxa3 ([Stockfish 120719 64 BMI2] 62:+5.20) 40...Be8 41.Kc2 Kf7 42.Kc3 Ke6 43.Kb4 g5 44.a4 Kd6 45.a5 Kc7 46.a6 Kb8 47.Bb5 Bh5 48.Bd3 Bg6 49.Kb5 Kc7 50.g3 Be8+ 51.Kb4 Bd7 52.fxg5 fxg5 53.Bb5 Bc8 54.a7 Bb7 55.Be2 Bc6 56.Ba6 Ba8 57.Kb3 Kc6 58.Kc3 Kc7 59.Kd2 Bc6 60.Kd1 Kd6 61.Kc1 Ke7 62.Kb2 Kd6 63.Kc3 Kc7 64.Kd2 Kd6 65.Bc8 b5 66.Bxf5 Kc7 67.Ke2 b4 68.Kf3 b3 69.Kg4 b2 70.Kxg5 Kb7 71.g4 Bd7 72.Bb1 Be6 73.Kf4 Bg8 74.g5 Kxa7 75.Ke5 Ka6 76.Kd6 Kb5 77.e4 dxe4 78.Bxe4 Bb3 79.g6 Kc4 80.Ke5 Kc3 81.g7 Bf7 82.d5 ) 39...Bxa3 40. bxa3 Ba4 41. Ke1 Kf7 42. Kd2 Ke7 43. Kc3 Kd6 44. Bd3 Kc7 45. Kb4 Bd1 46. Kb5 Bg4 47. Ka6 Bd1 48. Bb5 Bc2 49. Be8 Bd3+ 50. Ka7 g5 51. g3 Be2 52. Ba4 Bd3 53. Bb3 gxf4 {Game over! 1-0}[/pgn]

todd · Post by **todd** » Sun Jul 21, 2019 6:20 pm

A similar (but much simpler!) position occurred a few days ago in the US Junior championship game Li-Cervantes, and even in this simplified position, it takes SF a while to realize that black is winning.

[d]8/4b1k1/4p3/3pPp2/3P1P2/4B1K1/8/8 w - - 0 51

(the conclusion to the game can be seen here: https://www.chessbomb.com/arena/2019-us ... iro_Thalia)

White was just 9 years old and voluntarily traded queens to land in this position, thinking it was drawn. She learned a valuable lesson about just how dangerous these bishop endgames with fixed pawns on the wrong color can be (zugzwangs are everywhere!)

I've encountered the phenomenon in this thread quite often in bishop endgames and some other types of endgames where zugzwangs are commonplace (0.00 until quite high depth, until suddenly it's not... or you have to "show" SF the plan for some moves, and then finally it gets it at some point).

Zenmastur · Post by **Zenmastur** » Mon Jul 22, 2019 12:05 am

I guess I need to read my posts after I post them, either that or not make posts in the middle of the night. In any case here is a corrected post.

[d]8/3b2k1/1p1b1pp1/3p1p2/1P1P1P2/R3P3/1P3KP1/r3NB2 b - - 4 37

Code: Select all

( [Stockfish 120719 64 BMI2] 51:+3.32 37...Rxa3 38.bxa3 Ba4 39.Bd3 Kf7 40.Nf3 Be8 41.Nd2 Ke7 42.Nb1 Bf7 
 43.Nc3 Kd7 44.Ke2 Be7 45.Bb5+ Kc7 46.Kd2 Bf8 47.Bd3 Bh6 48.Kc2 Bf8 49.Na4 Be6 50.Kb3 Be7 51.Nc3 Bd8 52.Bb5
 Bf7 53.Be2 Kd6 54.Kc2 Be6 55.Bd3 Be7 56.a4 Kc6 57.Bb5+ Kb7 58.Kb3 Bf7 59.Ka3 Bd8 60.Na2 Be7 61.Kb2 Bd6 
   62.Kb3 Bc7 63.Be2 Bd8 64.Bd3 Be8 65.Nc3 Bf7 )

Not great...

[d]8/3b2k1/1p3pp1/3p1p2/1b1P1P2/R3P3/1P4P1/4KB2 w - - 0 39

Code: Select all

( [Stockfish 120719 64 BMI2] 47:+5.73  39.Kd1 Kf7 40.Ra6 Ba5 41.Ra7 Ke6 42.Bd3 Be8 43.Ke2 Bd7 44.Bc2 Kd6 45.Rb7 Ke6 
 46.Kf3 Bc6 47.Rg7 Be8 48.Bb3 Bd2 49.Rb7 Ba5 50.Rb8 Bb5 51.Bc2 Bd7 52.Rh8 Ke7 53.Bb3 Be6 54.Rh7+ Kd8 55.Rb7 Ke8 56.Rb8+ 
 Ke7 57.Ke2 Kd6 58.Ba4 b5 59.Bxb5 g5 60.Rb7 Bc8 61.Ra7 Bb6 62.Ra8 Be6 63.Kd3 Kc7 64.Rf8 Kd6 65.Rxf6 gxf4 66.exf4 Ke7 
 67.Rh6 )
 
( [Stockfish 120719 64 BMI2] 63:+5.20 39.Kd1 Bxa3 40.bxa3 Be8 41.Kc2 Kf7 42.Kc3 Ke6 43.Kb4 g5 44.a4 Kd6 45.a5 Kc7 46.a6
 Kb8 47.Bb5 Bh5 48.Bd3 Bg6 49.Kb5 Kc7 50.g3 Be8+ 51.Kb4 Bd7 52.fxg5 fxg5 53.Bb5 Bc8 54.a7 Bb7 55.Be2 Bc6 56.Ba6 Ba8 
 57.Kb3 Kc6 58.Kc3 Kc7 59.Kd2 Bc6 60.Kd1 Kd6 61.Kc1 Ke7 62.Kb2 Kd6 63.Kc3 Kc7 64.Kd2 Kd6 65.Bc8 b5 66.Bxf5 Kc7 67.Ke2 
 b4 68.Kf3 b3 69.Kg4 b2 70.Kxg5 Kb7 71.g4 Bd7 72.Bb1 Be6 73.Kf4 Bg8 74.g5 Kxa7 75.Ke5 Ka6 76.Kd6 Kb5 77.e4 dxe4 78.Bxe4
  Bb3 79.g6 Kc4 80.Ke5 Kc3 81.g7 Bf7 82.d5 )

He let you off the hook by not playing 39.Kd1!

[pgn]1.d4 d5 2.Bf4 c5 3.c3 Nf6 4.e3 e6 5.Nd2 Nc6 6.Ngf3 Nh5 7.Bg5 f6 8.Bh4 g6 9.Be2 Ng7 10.Bg3 cxd4 11.cxd4 Nf5 12.O-O Kf7 13.a3 h5 14.Nh4 Nxg3 15.hxg3 Kg7 16.f4 Bd7 17.Nb3 b6 18.Bd3 Ne7 19.Rc1 Be8 20.g4 Rc8 21.Qf3 hxg4 22.Qxg4 Rh6 23.Nd2 Bd7 24.Qg3 Qe8 25.Ndf3 Nf5 26.Nxf5+ exf5 27.Rxc8 Qxc8 28.Qe1 Bd6 29.Kf2 b5 30.Qa5 Qb7 31.Rc1 Rh8 32.Bf1 Qb6 33.Qxb6 axb6 34.Ne1 b4 35.axb4 Ra8 36.Rc3 Ra1 37.Ra3 Rxe1 38.Kxe1 Bxb4+ 39.Kf2 ( 39.Kd1 Kf7 40.Ra6 Ba5 41.Ra7 Ke6 42.Bd3 Be8 43.Ke2 Bd7 44.Bc2 Kd6 45.Rb7 Ke6 46.Kf3 Bc6 47.Rg7 Be8 48.Bb3 Bd2 49.Rb7 Ba5 50.Rb8 Bb5 51.Bc2 Bd7 52.Rh8 Ke7 53.Bb3 Be6 54.Rh7+ Kd8 55.Rb7 Ke8 56.Rb8+ Ke7 57.Ke2 Kd6 58.Ba4 b5 59.Bxb5 g5 60.Rb7 Bc8 61.Ra7 Bb6 62.Ra8 Be6 63.Kd3 Kc7 64.Rf8 Kd6 65.Rxf6 gxf4 66.exf4 Ke7 67.Rh6 ) ( 39.Kd1 Bxa3 40.bxa3 Be8 41.Kc2 Kf7 42.Kc3 Ke6 43.Kb4 g5 44.a4 Kd6 45.a5 Kc7 46.a6 Kb8 47.Bb5 Bh5 48.Bd3 Bg6 49.Kb5 Kc7 50.g3 Be8+ 51.Kb4 Bd7 52.fxg5 fxg5 53.Bb5 Bc8 54.a7 Bb7 55.Be2 Bc6 56.Ba6 Ba8 57.Kb3 Kc6 58.Kc3 Kc7 59.Kd2 Bc6 60.Kd1 Kd6 61.Kc1 Ke7 62.Kb2 Kd6 63.Kc3 Kc7 64.Kd2 Kd6 65.Bc8 b5 66.Bxf5 Kc7 67.Ke2 b4 68.Kf3 b3 69.Kg4 b2 70.Kxg5 Kb7 71.g4 Bd7 72.Bb1 Be6 73.Kf4 Bg8 74.g5 Kxa7 75.Ke5 Ka6 76.Kd6 Kb5 77.e4 dxe4 78.Bxe4 Bb3 79.g6 Kc4 80.Ke5 Kc3 81.g7 Bf7 82.d5 ) 39...Bxa3 40. bxa3 Ba4 41. Ke1 Kf7 42. Kd2 Ke7 43. Kc3 Kd6 44. Bd3 Kc7 45. Kb4 Bd1 46. Kb5 Bg4 47. Ka6 Bd1 48. Bb5 Bc2 49. Be8 Bd3+ 50. Ka7 g5 51. g3 Be2 52. Ba4 Bd3 53. Bb3 gxf4 {1-0}[/pgn]

Regards,

Zenmastur

MikeB · Post by **MikeB** » Tue Jul 23, 2019 6:51 am

Ovyron wrote: ↑Sat Jul 20, 2019 8:44 am I just lost my first ICCF game since 2015, and I still don't know what happened.

At the end of 2017 I reached this endgame:

[d]8/3b2k1/1p3pp1/3p1p2/3P1P2/P3P3/5KP1/5B2 b - -

I analyzed it thoroughly and concluded it was an easy draw, as I couldn't find any progress for white. There were positions where Stockfish showed 0.00 up to depth 60. There were positions where Stockfish wouldn't show any progress up to depth 80 o_O

Note that my opponent had what I believed were more advantageous positions before, and he abandoned them for this endgame, which makes me believe he knew it was winning, which means this position is a white to move and mate in N.

I guess my analysis was done with engines that are now very updated, but I'd still like to know what's going on.

Full Pgn:

[pgn]1. d4 d5 2. Bf4 c5 3. c3 Nf6 4. e3 e6 5. Nd2 Nc6 6. Ngf3 Nh5 7. Bg5 f6 8. Bh4 g6 9. Be2 Ng7 10. Bg3 cxd4 11. cxd4 Nf5 12. O-O Kf7 13. a3 h5 14. Nh4 Nxg3 15. hxg3 Kg7 16. f4 Bd7 17. Nb3 b6 18. Bd3 Ne7 19. Rc1 Be8 20. g4 Rc8 21. Qf3 hxg4 22. Qxg4 Rh6 23. Nd2 Bd7 24. Qg3 Qe8 25. Ndf3 Nf5 26. Nxf5+ exf5 27. Rxc8 Qxc8 28. Qe1 Bd6 29. Kf2 b5 30. Qa5 Qb7 31. Rc1 Rh8 32. Bf1 Qb6 33. Qxb6 axb6 34. Ne1 b4 35. axb4 Ra8 36. Rc3 Ra1 37. Ra3 Rxe1 38. Kxe1 Bxb4+ 39. Kf2 Bxa3 40. bxa3 Ba4 41. Ke1 Kf7 42. Kd2 Ke7 43. Kc3 Kd6 44. Bd3 Kc7 45. Kb4 Bd1 46. Kb5 Bg4 47. Ka6 Bd1 48. Bb5 Bc2 49. Be8 Bd3+ 50. Ka7 g5 51. g3 Be2 52. Ba4 Bd3 53. Bb3 gxf4 54. exf4 Be4 55. Ba4 Bf3 56. Ka6 Be2+ 57. Bb5 Bg4 58. Bd3 Bh3 59. Kb5 Kb7 60. a4 Kc7 61. a5 bxa5 62. Kxa5 Kc6 63. Bb5+ Kc7 64. Ka6 Bg2 65. Be8 Bf1+ 66. Ka5 Bd3 67. Bg6 Bc2 68. Kb5 Kd6 69. Bh5 Bd3+ 70. Kb6 Bb1 71. Kb7 Be4 72. Kc8 Ke7 73. Kc7 Bd3 74. Kc6 Ke6 75. Be8 Bb1 76. Kc5 Be4 77. Bb5 Bh1 78. Ba6 Be4 79. Bb7 Kd7 80. Bxd5 Bc2 81. Bf7 Bd1 82. Bc4 Bf3 83. Bd3 Be4 84. Kc4 {Black Resigns. 1-0} [/pgn]

My impressions and with using some backward analysis, you had totally equalize with move 28. Bd6 - always a good time to offer draw here ;>)

The first weakness was 29 ...b5 which allowed Qa5, the next series of moves are pretty much straight foward, but 36.. Ra1 was not the best move I'm afraid. After that everything was more or less forced until you get to 39. Kf2 by white, 39. Kd1 would have been faster . At this point, it appears you were lost, but if there was any doubt, you were certainly lost after 53 gxf4. That move alone change the scoring % from under 60% to over 70% for white. When one gets over 70% in a ICCF game, the winning side should expect to to win. The game was well played, you were a little bit unlucky in some respects and the position required some very deep analysis that is always much easier to see after the fact using backward analysis. Congrats on your unbeaten streak , that's an accomplishment!

Ovyron · Post by **Ovyron** » Tue Jul 23, 2019 10:38 am

MikeB wrote: ↑Tue Jul 23, 2019 6:51 amMy impressions and with using some backward analysis, you had totally equalize with move 28. Bd6 - always a good time to offer draw here ;>)

Thanks Mike, I had a score that was positive for black, higher than what white gets on the opening position (maybe it was wrong, but that's what I thought.) I have many games won from the black side, because if your opponent plays bad enough to allow you to equalize, it may play bad enough to let you win, so I only offer draw in trivially drawn positions.

MikeB wrote: ↑Tue Jul 23, 2019 6:51 amAt this point, it appears you were lost, but if there was any doubt, you were certainly lost after 53 gxf4. That move alone change the scoring % from under 60% to over 70% for white.

I'm not a believer of such scoring, if the position at move 40 is a mate for white, then surely it should show 100% for white. Then we'd know if at some point White gave up the win, and black gave up the draw with 53 gxf4, which would lead to another 100% score for white.

Zenmastur · Post by **Zenmastur** » Tue Jul 23, 2019 11:40 am

You were lost after 38. .... Bxb4. If your opponent would have played 39.Kd1! the game was effectively over. I looked at this variation in great depth. I have no clue why he didn't find this move. I didn't have any trouble finding it using my "normal" analysis method. i.e. the exact same methods I use during a CC game.

I also did some experiments with the position after 53. ...gxf4 and came to a not too surprising conclusion. When I tested the position with different amounts of cache I found that gxf4 was much more likely to be at or near the top of a Multi-PV 4 list. I tested each configuration multiple times and it varied from one time to the next but overall the more cache the less likely this move was to be at the top of the list from one iteration to the next. I used a relatively recent version of SF in my testing "stockfish_17121709_x64_bmi2"

I tested cache sizes of 16mb, 128mb, 1024mb, 8,192mb, and 32,768mb. So, I suggest you either adjust your analysis regimen or use more ram for your TT. If you don't have enough ram I suggest you buy more.

Regards,

Zenmastur

What's up with this endgame?

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