A Piece En Prise for 27 moves consecutively!

[MMarco]

In this game Stockfish 14.1 put a knight en prise for 27 moves in a row! From move 14 till white (Lc0 31.1 + LS 15.0) finally captured it on move 41. Note that the black knight could have escaped throught d3 (but at the cost of a pawn), but Stockfish preferred to let it en prise fot that long. A rare occurence!

[pgn][Event "My Tournament"]
[Site "?"]
[Date "2024.09.02"]
[Round "14"]
[White "LS 15.0"]
[Black "Stockfish 14.1"]
[Result "1/2-1/2"]
[ECO "B00"]
[GameDuration "00:02:09"]
[GameEndTime "2024-09-02T04:22:03.544 Est (heure d’été)"]
[GameStartTime "2024-09-02T04:19:54.481 Est (heure d’été)"]
[Opening "Owen defense"]
[PlyCount "160"]
[TimeControl "30+0.5"]

1. e4 {book} b6 {book} 2. d4 {book} Bb7 {book} 3. Bd3 {book} e6 {book}
4. Nf3 {book} c5 {-0.97/25 4.21s} 5. c3 {+0.73/15 2.39s} Nf6 {-1.06/25 0s}
6. Qe2 {+0.68/16 1.24s} d5 {-1.05/25 2.71s} 7. e5 {+0.62/16 0.38s}
Nfd7 {-1.02/21 0.20s} 8. O-O {+0.62/14 0.21s} Nc6 {-1.10/20 0.84s}
9. a3 {+0.62/14 2.47s} Be7 {-0.79/20 0.83s} 10. b4 {+0.63/16 0.28s}
c4 {-0.80/23 0.77s} 11. Bc2 {+0.59/17 1.43s} b5 {-0.89/26 0s}
12. a4 {+0.58/17 0.64s} bxa4 {-0.99/26 0.92s} 13. h4 {+0.58/18 0.97s}
a5 {-0.73/25 2.93s} 14. b5 {+0.60/17 0.21s} Nb4 {-0.64/23 0.50s}
15. Bxa4 {+0.60/16 0.57s} Nb6 {-0.74/23 0.60s} 16. Ne1 {+0.55/15 2.47s}
Bxh4 {-0.68/25 0.33s} 17. Qg4 {+0.43/13 3.65s} Kf8 {-0.88/24 1.70s}
18. Bd1 {+0.39/22 0.21s} h6 {-0.79/21 0.85s} 19. Bd2 {+0.44/11 2.77s}
Be7 {-0.33/20 0.91s} 20. Be2 {+0.31/13 0.88s} g6 {-0.48/22 1.53s}
21. Qf3 {+0.28/10 0.78s} Ke8 {-0.24/24 1.88s} 22. Kh2 {+0.73/10 1.00s}
Qd7 {-0.45/22 0.28s} 23. Na3 {+0.53/11 0.55s} Qc7 {-0.42/24 2.68s}
24. Qg3 {+0.45/13 0.31s} Kd7 {-0.52/24 3.85s} 25. Kg1 {+0.67/10 1.38s}
Qb8 {-0.44/27 5.16s} 26. Qf3 {+0.64/9 1.86s} Ke8 {-0.67/27 0.32s}
27. Qe3 {+0.48/10 1.49s} Bg5 {-0.05/20 1.30s} 28. f4 {+0.41/9 0.49s}
Be7 {-0.25/22 0.32s} 29. Bc1 {+0.37/9 1.08s} h5 {-0.24/22 0.001s}
30. Rf3 {+0.37/9 1.41s} Kd7 {-0.06/27 3.61s} 31. Qd2 {+0.46/8 1.15s}
h4 {0.00/24 0.17s} 32. Kh2 {+0.57/8 0.90s} Qf8 {-0.12/19 1.33s}
33. Nb1 {+0.44/10 0.74s} Kc7 {-0.16/21 1.40s} 34. Qb2 {+0.39/11 0.29s}
Rg8 {-0.14/20 0.21s} 35. Kg1 {+0.42/10 2.06s} Qe8 {-0.28/25 1.44s}
36. Na3 {+0.36/13 0.21s} Na4 {-0.13/23 0.41s} 37. Qb1 {+0.41/10 1.34s}
Nb6 {-0.28/27 0.67s} 38. Bf1 {+0.41/10 1.54s} Qf8 {-0.07/20 0.32s}
39. Rh3 {+0.37/11 0.44s} Rh8 {0.00/26 1.45s} 40. Be2 {+0.40/9 1.14s}
Bc8 {0.00/23 0.24s} 41. cxb4 {+0.65/17 0.61s} axb4 {-1.12/23 0.79s}
42. Nac2 {+0.64/22 0.21s} Rxa1 {-1.15/21 0.26s} 43. Nxa1 {+0.61/22 0.21s}
Bd7 {-0.99/23 0.50s} 44. Bd2 {+0.63/21 2.44s} Qa8 {-0.54/25 0s}
45. Nec2 {+0.61/28 0.21s} c3 {-0.29/19 0.29s} 46. Be1 {+0.53/16 1.10s}
Nc4 {-0.62/21 0.005s} 47. Nb3 {+0.45/14 1.41s} Bxb5 {-0.44/26 0s}
48. Nc5 {+0.57/19 0.68s} Bxc5 {0.00/25 0.001s} 49. dxc5 {+0.42/26 0.40s}
Na3 {-0.28/27 0.92s} 50. Nxa3 {+0.21/28 0.22s} bxa3 {0.00/25 0.30s}
51. Bxc3 {+0.19/25 0.24s} Bxe2 {-0.02/26 0.63s} 52. Qb6+ {+0.18/25 0.26s}
Kd7 {-0.01/24 0.20s} 53. Qd6+ {+0.13/25 1.77s} Kc8 {0.00/28 0.001s}
54. c6 {+0.13/25 0.20s} Qa7+ {0.00/27 0.63s} 55. Kh2 {+0.12/24 0.21s}
Rd8 {0.00/26 0.61s} 56. Qb4 {+0.10/24 0.21s} d4 {0.00/28 0.31s}
57. Be1 {+0.10/22 0.21s} d3 {0.00/28 0.48s} 58. Bf2 {+0.10/19 0.95s}
Qa6 {0.00/29 0s} 59. Bxh4 {+0.10/12 0.21s} Rg8 {0.00/29 0.66s}
60. Qd6 {0.00/11 2.08s} Qa7 {0.00/33 0s} 61. c7 {0.00/9 0.21s}
Qa5 {0.00/31 0.72s} 62. Be1 {0.00/12 0.21s} Qa4 {0.00/32 0.49s}
63. Rh7 {+0.19/17 1.58s} d2 {0.00/28 0.63s} 64. Bxd2 {+0.11/18 0.53s}
Bc4 {0.00/29 0.13s} 65. Rxf7 {+0.05/16 0.49s} Rh8+ {0.00/32 0.34s}
66. Kg3 {+0.04/16 0.74s} Qb3+ {0.00/35 0.15s} 67. Kf2 {+0.02/13 1.41s}
Qd3 {0.00/39 0s} 68. Ba5 {+0.04/13 0.21s} Qe2+ {0.00/43 0.66s}
69. Kg3 {+0.02/1 0.008s} Qe3+ {0.00/41 0.83s} 70. Kg4 {+0.01/1 0.007s}
Qe2+ {0.00/45 0.72s} 71. Kg5 {+0.02/7 2.06s} Qh5+ {0.00/53 0s}
72. Kf6 {+0.01/1 0.002s} Qh4+ {0.00/55 0.79s} 73. Kg7 {0.00/1 0.005s}
Qh6+ {0.00/54 0.82s} 74. Kf6 {0.00/1 0s} Qh4+ {0.00/55 1.01s}
75. Kg7 {0.00/1 0.005s} Qh6+ {0.00/55 0.67s} 76. Kf6 {0.00/1 0.003s}
Qxf4+ {0.00/59 1.29s} 77. Kg7 {+0.01/1 0.001s} Qh6+ {0.00/59 0.50s}
78. Kf6 {0.00/1 0.004s} Qf4+ {0.00/59 2.80s} 79. Kg7 {0.00/1 0.003s}
Qh6+ {0.00/58 0.17s} 80. Kf6 {0.00/1 0.002s}
Qf4+ {0.00/62 0.46s, Draw by 3-fold repetition} 1/2-1/2[/pgn]

[Ajedrecista]

Hello:

Good find! I found other long examples at Tim Krabbé's excellent site:

Chess records — Longest en prise

Miles - Ljubojevic, Tilburg 1986 (27 moves: from move 12 to move 39):

[pgn][Site "Tilburg NED"]
[Date "1986.10.??"]
[EventDate "1986.10.??"]
[Round "12"]
[Result "1-0"]
[White "Miles, Anthony J"]
[Black "Ljubojevic, Ljubomir"]
[ECO "A04"]
[WhiteElo "2500"]
[BlackElo "2605"]
[PlyCount "119"]

1. Nf3 c5 2. c4 g6 3. e4 Bg7 4. d4 Nc6 5. dxc5 Qa5+ 6. Nfd2 Qxc5 7. Be2 d6 8. O-O Nd4 9. Bd3 Nf6 10. Nb3 Nxb3 11. axb3 Ng4 12. h3 h5 13. Qd2 Qe5 14. f4 Qc5+ 15. Kh1 Bd7 16. Nc3 e6 17. Qe2 Bd4 18. Bd2 Qb6 19. Nd1 a6 20. Ba5 Qa7 21. Bb4 Qb6 22. Ba5 Qc5 23. Qe1 e5 24. Bb4 Qb6 25. Ba5 Qa7 26. f5 gxf5 27. exf5 Bc6 28. Be4 Kd7 29. f6 Rag8 30. Bxc6+ bxc6 31. Qe4 Qb7 32. Bc3 Ba7 33. b4 Kc8 34. c5 dxc5 35. Qf5+ Kb8 36. Bxe5+ Ka8 37. bxc5 Bxc5 38. Bg3 Ba7 39. Qd3 Ne3 40. Rf3 Rd8 41. Bd6 Nxd1 42. Qxd1 Rhg8 43. b4 Rg5 44. Rd3 c5 45. Bg3 Rgd5 46. Rxd5 Qxd5 47. Qa4 cxb4 48. Qxa6 Qb7 49. Qf1 Rd7 50. Bf2 Qc6 51. Bg1 Rb7 52. Qf2 Qd7 53. Qf3 Kb8 54. Qf4+ Ka8 55. Qe4 Kb8 56. Bxa7+ Rxa7 57. Qxb4+ Ka8 58. Qf8+ Kb7 59. Rxa7+ Kxa7 60. Qe7 1-0[/pgn]

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Morozevich - Vachier-Lagrave, Biel 2009 (24 moves: from move 27 to move 51):

[pgn][Site "Biel SUI"]
[Date "2009.07.28"]
[EventDate "2009.07.19"]
[Round "8"]
[Result "0-1"]
[White "Alexander Morozevich"]
[Black "Maxime Vachier-Lagrave"]
[ECO "B80"]
[WhiteElo "2751"]
[BlackElo "2703"]
[PlyCount "152"]

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. f3 e6
7. Be3 b5 8. Qd2 Nbd7 9. g4 h6 10. O-O-O b4 11. Nce2 Qc7
12. h4 d5 13. Nf4 e5 14. Nfe6 fxe6 15. Nxe6 Qa5 16. exd5 Qxa2
17. Qd3 Kf7 18. g5 Nxd5 19. Bh3 Nxe3 20. Nd8+ Ke7 21. Nc6+ Kf7
22. g6+ Kg8 23. Qxe3 Bc5 24. Qe4 Nf8 25. Rd8 Bb7 26. Rxa8 Bxa8
27. h5 Rh7 28. Re1 Bxc6 29. Qxc6 Bd4 30. Kd2 Qxb2 31. Qc4+ Kh8
32. Kd3 a5 33. Qc8 Qa3+ 34. Ke4 b3 35. cxb3 a4 36. Rb1 Qb4
37. Qc4 Qb7+ 38. Qd5 Qb4 39. Qc4 Qd2 40. Bg4 a3 41. Qf7 Qc2+
42. Kd5 Qc5+ 43. Ke4 a2 44. Rc1 a1=Q 45. Rxc5 Bxc5 46. Qd5
Qe1+ 47. Kd3 Qd1+ 48. Kc4 Qxd5+ 49. Kxd5 Ba3 50. Bf5 Kg8
51. Kxe5 Rh8 52. Kd5 Nh7 53. gxh7+ Kf7 54. Bg6+ Kf6 55. f4 Bc1
56. f5 Bd2 57. Kd6 Be1 58. Kd7 Bb4 59. Kc7 Ke5 60. Kd7 Ba3
61. Kc6 Kd4 62. Kc7 Kc3 63. Kd7 Kb4 64. Kd6 Kxb3+ 65. Kd5 Bb2
66. Kd6 Bf6 67. Kc5 Kc3 68. Kd6 Kd4 69. Kc6 Rd8 70. Kb6 Kd5
71. Kc7 Kc5 72. Bf7 g5 73. fxg6 Rd6 74. Be8 Be5 75. Kb7 Rb6+
76. Kc8 Kd6 0-1[/pgn]

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Finally, Chess History excellent site illustrates the concept with some games:

En prise (Chess Term) by Edward Winter

I do not know if there are studies or problems with such long en prise themes.

Regards from Spain.

Ajedrecista.

[Jouni]

SF 16.1 thinks You can take it immediately. 40 plies analysis by Stockfish 16.1:

1. +/= (0.70): 15.cxb4 axb4 16.Rxa4 Rxa4 17.Bxa4 h6 18.Be3 Qa5 19.Bc2 Qxb5 20.Nh2 h5 21.Nf3 Ba6 22.Nc3 Qa5 23.Rc1 bxc3 24.Rb1 Bb5 25.Ng5 Bc6 26.Qf3 Bxg5 27.Bxg5 Qa7 28.Qxc3 0-0 29.Ra1 Qb8 30.Qd2 Rc8 31.Qe2 g6 32.Rb1 Qa7 33.Qe3 Rb8 34.Rxb8+ Qxb8 35.Bf6 Kh7 36.Qg5 Qf8 37.Qxh5+ Qh6 38.Qxh6+ Kxh6 39.g4
2. +/= (0.67): 15.Bxa4 Nd3 16.Ba3 Nb6 17.Bc2 a4 18.Bxd3 cxd3 19.Qxd3 h6 20.Bc5 Qc7 21.Bxe7 Qxe7 22.Nbd2 0-0 23.Rfb1 Rac8 24.Nf1 Rc7 25.Ne3 Rfc8 26.Rc1 Nc4 27.Ra2 Qe8 28.Qb1 Ra8 29.Nxc4 dxc4 30.Qb4 Bxf3 31.gxf3 Rb7 32.Rb1 f6

[MMarco]

It is likely that if you use Stockfish 16.1 at depth 40 you'll find suboptimal moves in Tim Krabbé's Chess records or in the game I posted between older Stockfish and Lc0 net at 30s + 0.5s. It doesn't change the fact that outside cooked positions or chess problems, a piece en prise for that long is a rarity.

I could replicate Stockfish 16.1 preferrence at depth 40, but note that at depth 46 (when I ended the analysis), Stockfish 16.1 changed its mind advocating not to take the knight at this point:

Code: Select all

[46] 0.73 Fxa4 Cd3 Fg5 h6 Fxe7 Dxe7 Fc2 Cb6 Fxd3 cxd3 Dxd3 a4 Cbd2 O-O Tfb1 Tfc8 g4 Cc4 Tb4 a3 g5 h5 De2 Cb2 Tb3 Cc4 Ce1 De8 Cd3 Ta5 Tab1 a2 Ta1 Txb5 Cc5 Tbxc5 dxc5 Cxd2 Txb7 Ce4 Dxa2 Cxc5 Ta7 Ce4 Ta8 Cxc3 Da7 Txa8 Dxa8 Dxa8 Txa8+ Rh7 Te8 d4 Tc8 Ce2+ Rf1

[46] 0.62 cxb4 axb4 Txa4 Txa4 Fxa4 h6 Fd2 Db6 De3 O-O Ch2 Tc8 Fc2 Dxb5 Cg4 Rf8 Cc3 bxc3 Fxc3 h5 Tb1 Da6 Ch2 Fc6 Df3 Rg8 Dxh5 Cf8 Ta1 Db7 Dg4 Ta8 Tb1 Dc7 Tc1 Fa4 Fb1 Fa3 Te1 Db6 h5 Fb2 Fxb2 Dxb2 h6 g6 Df4

d:47/67 1:Fxa4 t:9217 n:6572M nps:713k tb:496 h:100

In both cases (depth 40 and 46), the evals are close between the two moves and it will be difficult to identify the best move with certainty.