test positions from TCEC

[Uri Blass]

Note that I am not sure if there is a single solution

[d]1r2rk2/4ppbQ/3pR1p1/2q2bN1/1p5P/1P4P1/5PB1/4R1K1 w - - 2 41 bm Bf1

lc0 was surprised by this move and top engines needs some minutes to find it.

harder one

[d]1b2k3/2q5/p3b2p/2p1p3/P1P1PpP1/2B2P1P/1Q6/5BK1 w - - 2 41 bm Kh2

Stockfish expected it but lc0 failed to find it.

main line starts with Kh2 Qd6 Qb7 Bc7 h4 a5 h5 Kf8 Be1

[peter]

Very well!
Both with 30 threads of 16x3.5GHz CPU and 32 G hash, first one with MultiPV=2 after some Forward- Backward:

[d]1r2rk2/4ppbQ/3pR1p1/2q2bN1/1p5P/1P4P1/5PB1/4R1K1 w - - 0 1

Analysis by Stockfish dev-20241222-f656fdfa:

Code: Select all

1. +- (3.50):  1.Lf1! Ta8 2.Lc4 d5 3.h5 Ta1 4.h6 Dd4 5.hxg7+ Dxg7 6.Txa1 fxe6 7.Dxg7+ Kxg7 8.Le2 e5 9.f4 exf4 10.gxf4 Tc8 11.Lf3 d4 12.Ta7 Tc1+ 13.Kf2 Tc2+ 14.Kg3 Kf8 15.Tb7 Tc3 16.Txb4 d3 17.Kf2 d2 18.Ke2 d1D+ 19.Kxd1 Lc2+ 20.Kd2 Txb3 21.Td4 Lf5 22.Td8+ Kg7 23.Te8 e6 24.Te7+ Kf8 25.Tf7+ Ke8 26.Lc6+ Kd8 27.Td7+ Kc8 28.Td4 Tb2+ 29.Ke3 Tb3+ 30.Kf2 Kb8 31.Le4 Tb2+ 32.Ke3 Tb3+ 33.Ke2

2. +/= (0.56):  1.h5!? Lxe6 2.h6 Ld4 3.Sxe6+ fxe6 4.Te3 Tec8 5.Dxg6 Lxe3 6.h7 Lxf2+ 7.Kh1 Dh5+ 8.Dxh5 Kg7 9.Dg5+ Kh8 10.Dxe7 Ld4 11.Dxd6 Td8 12.Dxe6 Tf8 13.Kh2 Tb6 14.Lc6 Tbb8 15.Kg2 Lc3 16.Lf3 Tbd8 17.Lh5 Tb8 18.Lg6 Ta8 19.Dd5

Depth 35.

The second one indeed is even harder for SF, had to give in the first moves of your line to make the engine get a winning eval, yet there seem to be more than one winning move, again after some Forward- Backward, this time MultiPV=4, depth 50:

[d]1b2k3/2q5/p3b2p/2p1p3/P1P1PpP1/2B2P1P/1Q6/5BK1 w - - 0 1

Code: Select all

Analysis by Stockfish dev-20241222-f656fdfa:

1. +/- (1.59):  41.Kh2 Dd6 42.Db7 Lc7 43.h4 a5 44.h5 Kf8 45.Le1 Lf7 46.Da8+ Dd8 47.Da7 Lb6 48.Db7 Dd6 49.Lf2 Kg7 50.Kg2 Ld8 51.Da8 Lc7 52.Le2 Ld8 53.Kf1 Dc7 54.Da6 Lf6 55.Le1 Ld8 56.Lc3 De7 57.Da8 Lb6 58.Db8 Lc7 59.Db7 Dd6 60.Le1 Lb6 61.Lh4 Ld8 62.Lf2 Lb6 63.Dc8 Lc7 64.Lh4 Le6 65.De8 Lf7 66.De7 Dxe7 67.Lxe7 Lb6 68.Ld6 Kf6 69.Lb8 Ke6 70.Ld1 Lg8 71.Lc2 Kf6 72.Lb3 Lf7

2. +/- (1.54):  41.Le1 Da7 42.Lc3 Dc7 43.h4 Dd6 44.Db7 Lc7 45.Kh2 a5 46.h5 Kf8 47.Le1 Lf7 48.Da8+ Dd8 49.Da7 Lb6 50.Db7 Dd6 51.Lf2 Kg7 52.Kg2 Ld8 53.Da7 Lb6 54.Da8 Ld8 55.Db7 Lb6 56.Le2 Kf8 57.Kf1 Kg7 58.Ke1 Lc7 59.Da7 Lb6 60.Da8 Ld8 61.Dc8 Le7 62.Kf1 Db6 63.Dd7 Kf8 64.Le1 Ld8 65.Lc3 Le6 66.Db5 Dd6 67.Db7 Lc7 68.Le1 Lf7 69.Dc8+ Le8 70.Lf2 Lb6 71.Kg2 Kf7 72.Db7+ Ld7 73.Kf1 Kg7 74.Dd5 De6 75.Lh4 Kf7 76.Da8 Dd6 77.Dh8

3. +/- (1.51):  41.h4 Dd6 42.Kh2 Lc7 43.Db7 a5 44.h5 Kf8 45.Le1 Lf7 46.Lf2 Kg7 47.Kg2 Ld8 48.Da8 Lb6 49.Le2 Ld8 50.Kf1 Dc7 51.Da6 Le7 52.Le1 Ld8 53.Lc3 De7 54.Da8 Lb6 55.Db8 Lc7 56.Db7 Dd6 57.Le1 Lb6 58.Lh4 Ld8 59.Lf2 Lc7 60.Dc8 Lb6 61.Lh4 Lc7 62.Kf2 Dd4+ 63.Kg2 Dd6 64.Kf1 Lb6 65.Ke1 Lc7 66.Df5 Le8 67.g5 Lxh5 68.gxh6+ Dxh6 69.Le7 Dg6 70.Df8+ Kh7 71.Lxc5 Lb6 72.De7+ Kh6 73.Kd2 Lxc5 74.Dxc5 Df6 75.Dc7 Dg7 76.Db6+

4. +/- (1.49):  41.La5 Da7 42.Lc3 Dc7 43.Kh2 Dd6 44.Db7 Lc7 45.h4 a5 46.h5 Kf8 47.Le1 Dd1 48.Lh4 Dd2+ 49.Kg1 Dd6 50.Lf2 Lf7 51.Da8+ Kg7 52.Le2 Lb6 53.Kg2 Lc7 54.Dc8 Le6 55.Db7 Lf7 56.Kf1 Ld8 57.Da8 Lb6 58.Ke1 Ld8 59.Dc8 Lb6 60.Lh4 Lc7 61.Kf2 Lb6 62.Kf1 Lc7 63.Da8 Dd7 64.Db7 Dd6 65.Da7 Kf8 66.Da8+ Le8 67.Lf2 Lb6 68.Dc8 Lc7 69.Kg2 Kf7 70.Db7 Lxa4 71.Da7 Db6 72.Lxc5 Dxa7 73.Lxa7 Ld7 74.Kf2 Ld8 75.Ke1 a4 76.Lc5 Le7 77.Lxe7 Kxe7 78.Kd2 a3 79.Kc1
 

After pasting that, in depth 51 move order changed :

Code: Select all

1b2k3/2q5/p3b2p/2p1p3/P1P1PpP1/2B2P1P/1Q6/5BK1 w - - 0 1

Analysis by Stockfish dev-20241222-f656fdfa:

1. +- (1.61):  41.h4 Dd6 42.Db7 Lc7 43.Kh2 a5 44.h5 Kf8 45.Le1 Lf7 46.Lf2 Lb6 47.Kg2 Kg8 48.Da8+ Kg7 49.Le2 Le6 50.Lh4 Lf7 51.Dc8 Dd2 52.Kf1 Dd6 53.Ke1 Lc7 54.Da8 Dd7 55.Db7 Dd6 56.Dc8 Lb6 57.Kf1 Lc7 58.Db7 Kf8 59.Lf2 Lb6 60.Dc8+ Le8 61.Ke1 De7 62.Ld1 Dd6 63.Ke2 De7 64.Lb3 Dd6 65.Lc2 De7 66.Db8 La7 67.Da8 Lb6 68.Le1 Dd8 69.Da6 Kg8 70.Db7

2. +/- (1.59):  41.La5!? Da7 42.Lc3 Dc7 43.h4 Dd6 44.Db7 Lc7 45.Kh2 a5 46.h5 Kf8 47.Le1 Lf7 48.Lf2 Lb6 49.Kg2 Kg8 50.Da8+ Kg7 51.Le2 Ld8 52.Kf1 Dc7 53.Da6 Lg5 54.Le1 Ld8 55.Lc3 De7 56.Da8 Lb6 57.Db8 Lc7 58.Db7 Dd8 59.Le1 Dd6 60.Lh4 Ld8 61.Lf2 Lb6 62.Dc8 Le6 63.Da8 Lf7 64.Lh4 Dc7 65.Ke1 Dd6 66.Dc8 Lc7 67.Kf2 Lg8

3. +/- (1.60):  41.Kh2 Dd6 42.Db7 Lc7 43.h4 a5 44.h5 Kf8 45.Le1 Dd1 46.Lh4 Dd2+ 47.Kg1 Dd6 48.Lf2 Lf7 49.Kg2 Kg7 50.Le2 Ld8 51.Kf1 Lb6 52.Ke1 Ld8 53.Dc8 Lb6 54.Lh4 Lc7 55.Kf2 Dd4+ 56.Kg2 Dd6 57.Kg1 Lb6 58.Kf1 Lc7 59.Ke1 Lb6 60.Df5 Lc7 61.g5 Lxh5 62.gxh6+ Dxh6 63.Le7 Dg6 64.Df8+ Kh7 65.Lxc5 Lb6 66.De7+ Kh6 67.Kd2 Lxc5 68.Dxc5 Df6 69.Dc7 De6 70.Ld1 Le8 71.Dxa5 Dd6+ 72.Dd5 Db4+ 73.Ke2 Db2+ 74.Ke1 Db4+ 75.Kf1 Dc3 76.Dd6+ Kh5 77.De6 Lg6 78.Dg8 Da1 79.Dh8+ Kg5 80.Dd8+ Kh5 81.Dd7 Kh6 82.c5 Lf7 83.c6 Lc4+ 84.Kf2

4. +/- (1.52):  41.Le1 Da7 42.Lc3 Dc7 43.Kh2 Dd6 44.Db7 Lc7 45.h4 a5 46.h5 Kf8 47.Le1 Lf7 48.Lf2 Kg7 49.Kg2 Ld8 50.Da8 Lb6 51.Le2 Ld8 52.Kf1 Dc7 53.Da6 Le8 54.Ld1 Kh7 55.Ke2 Lf7 56.Lb3 Le8 57.Lc2 Kg7 58.Kd1 Le7 59.Kd2 Ld8 60.Kc1 Lf7 61.Lb3 Le8 62.Ld1 Lf7 63.Le1 Db6 64.Db5 Dc7 65.Lc3 Kf6 66.Lc2 Dd6 67.Lb3 Kg5 68.Db7 Kf6 69.Kc2 Dc7 70.Db5 Ke7 71.Le1 Le6 72.Lf2 Kd6 73.De8 De7 74.Dg6 Df6 75.Dh7 Lf7 76.Le1 Ke7 77.Df5 De6 78.Lf2 Kd6 79.Kd3 De7 80.Le1 Kc6 81.g5 Le6 82.Dg6 Dd7+ 83.Kc2 Lxg5 84.Lxa5 Df7 85.Lc3 Dxg6 86.hxg6 Lf6 87.Kd2 h5