interesting test position

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jdart
Posts: 4425
Joined: Fri Mar 10, 2006 5:23 am
Location: http://www.arasanchess.org

interesting test position

Post by jdart »

This position occurred in an online game:
[d]4r1k1/7p/p3n3/rpp2P2/P1R2P2/2P4P/5BK1/R7 b - - 0 29

Here, bxc4, as played in the game, loses, because it renders the Rook on a5 immovable. Nd4! (only move) draws for Black. Stockfish finds this pretty quicky, but my engine does not.

Part of the challenge in rejecting bxc4 is seeing that this position, after the continuation fxe6 Rxe6:

[d]6k1/7p/p3r3/r1p5/P1p2P2/2P4P/5BK1/R7 w - -

is winning for White. White is down material, but the Black Rook on a5 is trapped, and if White can get his Bishop to the a5-d8 diagonal, the Rook will be lost.
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Jouni
Posts: 3825
Joined: Wed Mar 08, 2006 8:15 pm
Full name: Jouni Uski

Re: interesting test position

Post by Jouni »

But too easy for top engines.

Code: Select all


Analysis by Stockfish 18:

1. =  (0.26): 1...Nd4 2.Bxd4 cxd4 3.Rxd4 Re3 4.c4 Rxa4 5.Rxa4 bxa4 6.c5 a3 7.Rc4 Kg7 8.c6 a2 9.Ra4 Kf6 10.Rxa2 Rc3 11.Ra5 Rxc6 12.Kf3 Rc3+ 13.Ke4 Rc4+ 14.Ke3 Rb4 15.Rxa6+ Kxf5 
2. +-  (3.00): 1...bxc4 2.fxe6 Rxe6 3.Bh4 Rd6 4.f5 Kf7 5.Kf3 Rd7 6.Ke4 Rd3 7.Bg5 Ke8 8.h4 Rh3 9.f6 h6 10.Bf4 Rxh4 11.Kf5 Kf7 12.Bg3 
3. +-  (3.24): 1...Ng7 2.Rxc5 Rf8 3.Kf3 Rxf5 4.Rc8+ Rf8 5.Rc6 Rxa4 6.Rxa4 bxa4 7.Rxa6 Rd8 8.Bd4 Nf5 9.Rxa4 Kf7 10.Ra7+ Ke6 11.Ra6+ Rd6 12.Rxd6+ Kxd6 13.Kg4 Ke6 14.Be5 Nh6+ 15.Kf3 Kd5 16.Ke3 Nf5+ 17.Kd3 Kc5 18.c4 Ng3
Old engine

Code: Select all


Analysis by Deep Fritz 12:

1. -/+  (-0.83): 29...bxc4 30.fxe6 Rxe6 31.Bg3 Kf7 32.f5 Re7 33.Kf3 Kg8 34.Bd6 Rd7 35.Be5 Kf7 36.Kf4 Re7 37.Ke4 h5 38.Kd5 h4 39.f6 Rd7+ 40.Kxc4 Rd8 41.Bc7 
2. =  (0.00): 29...Nd4 30.Bxd4 bxc4 31.Be5 Re7 32.Kf3 Rd7 33.f6 Kf7 34.Ke4 Ke6 35.f5+ Kf7 36.Rg1 Rxa4 37.Rg7+ Ke8 38.Rg8+ Kf7 
3. +-  (1.99): 29...Ng7 30.Rxc5 Rxa4 31.Rxa4 bxa4 32.Ra5 Re2 33.Rxa4 Nxf5 34.Rxa6 Rc2 35.Ra3 h5 36.Kf3 Kf7 37.Ra7+ Ke6 38.Ra6+ Kd7 39.Ra3 Ke6 40.Bg1 Kd7
Jouni
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Dann Corbit
Posts: 12835
Joined: Wed Mar 08, 2006 8:57 pm
Location: Redmond, WA USA

Re: interesting test position

Post by Dann Corbit »

I think it is a wonderful position.
I looked at the position without looking at the winning plan, and I had a devil of a time coming up with something besides that delicious rook. I guess most humans will take the rook.
I use a lot of SF derivatives for analysis.
The engines that had the largest difficulty were Arasan and Absurd (which is whiz-bang fun to play against, even though it beats my brains out)
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Analysis of G:\jdart-02-18-2026.epd
Analyzing engine: Stockfish-x64-native
2/18/2026 9:36:50 AM Level: 90 Seconds
Source : List of EPD/PGN files
G:\jdart-02-18-2026.epd
Colours : White moves=True, Black moves=True
Direction : forward
Games (PGN) : From 1 to 999999
Moves : All moves
Positions (EPD) : From 1 to 999999
Use Engine(s) : List
Stockfish-x64-native
Absurd-1.0
Arasanx-64-avx2
Biglep-260244-x64-avx2
Crystal-5-DK
Lc0-v0.32.1-BT4
Leptir-TI-MPV-PB-native
Rems-M-091024-avx2
Sun-15-mpv-avx2
Use seconds per move : 90 Seconds per move
Analysis Lines : Minimum search depth=2
Activate abort analysis : False
1) .. Ne6-d4 Ne6-d4 * 0 Seconds
1 of 1 matching moves
2/18/2026 9:38:24 AM, Total time: 12:01:34 AM Rated time: 00:00 = 0 Seconds

--------------------------------------------------------------------------------

Analysis of G:\jdart-02-18-2026.epd
Analyzing engine: Absurd-1.0
2/18/2026 9:36:50 AM Level: 60 Seconds
Source : List of EPD/PGN files
G:\jdart-02-18-2026.epd
Colours : White moves=True, Black moves=True
Direction : forward
Games (PGN) : From 1 to 999999
Moves : All moves
Positions (EPD) : From 1 to 999999
Use Engine(s) : List
Stockfish-x64-native
Absurd-1.0
Arasanx-64-avx2
Biglep-260244-x64-avx2
Crystal-5-DK
Lc0-v0.32.1-BT4
Leptir-TI-MPV-PB-native
Rems-M-091024-avx2
Sun-15-mpv-avx2
Use seconds per move : 90 Seconds per move
Analysis Lines : Minimum search depth=2
Activate abort analysis : False
1) .. Ne6-d4 b5xc4
0 of 1 matching moves
2/18/2026 9:40:07 AM, Total time: 12:03:16 AM Rated time: 01:30 = 90 Seconds

--------------------------------------------------------------------------------

Analysis of G:\jdart-02-18-2026.epd
Analyzing engine: Arasanx-64-avx2
2/18/2026 9:36:50 AM Level: 60 Seconds
Source : List of EPD/PGN files
G:\jdart-02-18-2026.epd
Colours : White moves=True, Black moves=True
Direction : forward
Games (PGN) : From 1 to 999999
Moves : All moves
Positions (EPD) : From 1 to 999999
Use Engine(s) : List
Stockfish-x64-native
Absurd-1.0
Arasanx-64-avx2
Biglep-260244-x64-avx2
Crystal-5-DK
Lc0-v0.32.1-BT4
Leptir-TI-MPV-PB-native
Rems-M-091024-avx2
Sun-15-mpv-avx2
Use seconds per move : 90 Seconds per move
Analysis Lines : Minimum search depth=2
Activate abort analysis : False
1) .. Ne6-d4 Ne6-d4 * 44 Seconds
1 of 1 matching moves
2/18/2026 9:41:46 AM, Total time: 12:04:55 AM Rated time: 00:44 = 44 Seconds

--------------------------------------------------------------------------------

Analysis of G:\jdart-02-18-2026.epd
Analyzing engine: Biglep-260244-x64-avx2
2/18/2026 9:36:50 AM Level: 60 Seconds
Source : List of EPD/PGN files
G:\jdart-02-18-2026.epd
Colours : White moves=True, Black moves=True
Direction : forward
Games (PGN) : From 1 to 999999
Moves : All moves
Positions (EPD) : From 1 to 999999
Use Engine(s) : List
Stockfish-x64-native
Absurd-1.0
Arasanx-64-avx2
Biglep-260244-x64-avx2
Crystal-5-DK
Lc0-v0.32.1-BT4
Leptir-TI-MPV-PB-native
Rems-M-091024-avx2
Sun-15-mpv-avx2
Use seconds per move : 90 Seconds per move
Analysis Lines : Minimum search depth=2
Activate abort analysis : False
1) .. Ne6-d4 Ne6-d4 * 0 Seconds
1 of 1 matching moves
2/18/2026 9:43:23 AM, Total time: 12:06:32 AM Rated time: 00:00 = 0 Seconds

--------------------------------------------------------------------------------

Analysis of G:\jdart-02-18-2026.epd
Analyzing engine: Crystal-5-DK
2/18/2026 9:36:50 AM Level: 60 Seconds
Source : List of EPD/PGN files
G:\jdart-02-18-2026.epd
Colours : White moves=True, Black moves=True
Direction : forward
Games (PGN) : From 1 to 999999
Moves : All moves
Positions (EPD) : From 1 to 999999
Use Engine(s) : List
Stockfish-x64-native
Absurd-1.0
Arasanx-64-avx2
Biglep-260244-x64-avx2
Crystal-5-DK
Lc0-v0.32.1-BT4
Leptir-TI-MPV-PB-native
Rems-M-091024-avx2
Sun-15-mpv-avx2
Use seconds per move : 90 Seconds per move
Analysis Lines : Minimum search depth=2
Activate abort analysis : False
1) .. Ne6-d4 Ne6-d4 * 3 Seconds
1 of 1 matching moves
2/18/2026 9:44:59 AM, Total time: 12:08:08 AM Rated time: 00:03 = 3 Seconds

--------------------------------------------------------------------------------

Analysis of G:\jdart-02-18-2026.epd
Analyzing engine: Lc0-v0.32.1-BT4
2/18/2026 9:36:50 AM Level: 60 Seconds
Source : List of EPD/PGN files
G:\jdart-02-18-2026.epd
Colours : White moves=True, Black moves=True
Direction : forward
Games (PGN) : From 1 to 999999
Moves : All moves
Positions (EPD) : From 1 to 999999
Use Engine(s) : List
Stockfish-x64-native
Absurd-1.0
Arasanx-64-avx2
Biglep-260244-x64-avx2
Crystal-5-DK
Lc0-v0.32.1-BT4
Leptir-TI-MPV-PB-native
Rems-M-091024-avx2
Sun-15-mpv-avx2
Use seconds per move : 90 Seconds per move
Analysis Lines : Minimum search depth=2
Activate abort analysis : False
1) .. Ne6-d4 Ne6-d4 * 0 Seconds
1 of 1 matching moves
2/18/2026 9:46:40 AM, Total time: 12:09:49 AM Rated time: 00:00 = 0 Seconds

--------------------------------------------------------------------------------

Analysis of G:\jdart-02-18-2026.epd
Analyzing engine: Leptir-TI-MPV-PB-native
2/18/2026 9:36:50 AM Level: 60 Seconds
Source : List of EPD/PGN files
G:\jdart-02-18-2026.epd
Colours : White moves=True, Black moves=True
Direction : forward
Games (PGN) : From 1 to 999999
Moves : All moves
Positions (EPD) : From 1 to 999999
Use Engine(s) : List
Stockfish-x64-native
Absurd-1.0
Arasanx-64-avx2
Biglep-260244-x64-avx2
Crystal-5-DK
Lc0-v0.32.1-BT4
Leptir-TI-MPV-PB-native
Rems-M-091024-avx2
Sun-15-mpv-avx2
Use seconds per move : 90 Seconds per move
Analysis Lines : Minimum search depth=2
Activate abort analysis : False
1) .. Ne6-d4 Ne6-d4 * 0 Seconds
1 of 1 matching moves
2/18/2026 9:48:29 AM, Total time: 12:11:38 AM Rated time: 00:00 = 0 Seconds

--------------------------------------------------------------------------------

Analysis of G:\jdart-02-18-2026.epd
Analyzing engine: Rems-M-091024-avx2
2/18/2026 9:36:50 AM Level: 60 Seconds
Source : List of EPD/PGN files
G:\jdart-02-18-2026.epd
Colours : White moves=True, Black moves=True
Direction : forward
Games (PGN) : From 1 to 999999
Moves : All moves
Positions (EPD) : From 1 to 999999
Use Engine(s) : List
Stockfish-x64-native
Absurd-1.0
Arasanx-64-avx2
Biglep-260244-x64-avx2
Crystal-5-DK
Lc0-v0.32.1-BT4
Leptir-TI-MPV-PB-native
Rems-M-091024-avx2
Sun-15-mpv-avx2
Use seconds per move : 90 Seconds per move
Analysis Lines : Minimum search depth=2
Activate abort analysis : False
1) .. Ne6-d4 Ne6-d4 * 0 Seconds
1 of 1 matching moves
2/18/2026 9:50:06 AM, Total time: 12:13:15 AM Rated time: 00:00 = 0 Seconds

--------------------------------------------------------------------------------

Analysis of G:\jdart-02-18-2026.epd
Analyzing engine: Sun-15-mpv-avx2
2/18/2026 9:36:50 AM Level: 60 Seconds
Source : List of EPD/PGN files
G:\jdart-02-18-2026.epd
Colours : White moves=True, Black moves=True
Direction : forward
Games (PGN) : From 1 to 999999
Moves : All moves
Positions (EPD) : From 1 to 999999
Use Engine(s) : List
Stockfish-x64-native
Absurd-1.0
Arasanx-64-avx2
Biglep-260244-x64-avx2
Crystal-5-DK
Lc0-v0.32.1-BT4
Leptir-TI-MPV-PB-native
Rems-M-091024-avx2
Sun-15-mpv-avx2
Use seconds per move : 90 Seconds per move
Analysis Lines : Minimum search depth=2
Activate abort analysis : False
1) .. Ne6-d4 Ne6-d4 * 3 Seconds
1 of 1 matching moves
2/18/2026 9:51:43 AM, Total time: 12:14:52 AM Rated time: 00:03 = 3 Seconds
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chesskobra
Posts: 359
Joined: Thu Jul 21, 2022 12:30 am
Full name: Chesskobra

Re: interesting test position

Post by chesskobra »

Beautiful position indeed. Definitely worthy of entering a book of studies or puzzles.

Is it from a human game? If so, was the correct move played? If from lichess, it may have made it to the puzzle database.

I think it is not hard to see that if black takes the rook, then white bishop may try to reach the a5-d8 diagonal. But the exact calculation of taking the rook as well as the calculation of the correct move is not easy. But I am sure GMs would solve this easily.
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User avatar
Ajedrecista
Posts: 2200
Joined: Wed Jul 13, 2011 9:04 pm
Location: Madrid, Spain.

Re: Interesting test position.

Post by Ajedrecista »

Hello:

Thank you for sharing, Jon. I agree with Dann: it is a nice position. I would say that this is almost a problem looklike position.

------------
chesskobra wrote: ↑Wed Feb 18, 2026 7:47 pm[...]

Is it from a human game? If so, was the correct move played? If from lichess, it may have made it to the puzzle database.

[...]
jdart wrote: ↑Wed Feb 18, 2026 12:32 am This position occurred in an online game:
[...]

Here, bxc4, as played in the game, loses, because it renders the Rook on a5 immovable. [...]

[...]
Regards from Spain.

Ajedrecista.
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jdart
Posts: 4425
Joined: Fri Mar 10, 2006 5:23 am
Location: http://www.arasanchess.org

Re: interesting test position

Post by jdart »

FYI, the full game:
[pgn]
[Event "rated blitz game"]
[Site "lichess.org"]
[Date "2026.02.17"]
[Round "?"]
[White "ToromBot"]
[Black "ArasanX"]
[Result "1-0"]
[ECO "A15"]
[WhiteElo "2966"]
[BlackElo "2895"]
[WhiteFideId "-1"]
[BlackFideId "-1"]
[PlyCount "85"]
[GameId "2278634969243648"]
[EventDate "2026.??.??"]
[EventType "blitz"]

1. c4 Nf6 2. h3 e5 3. d3 d5 4. cxd5 Nxd5 5. Nf3 Bd6 6. Nc3 Nxc3 7. bxc3 O-O 8. g3 b6 9. Bg2 Bb7 10. O-O Nc6 11. d4 Re8 12. dxe5 Bxe5 13. Nxe5 Rxe5 14. Bf4 Re7 15. Qxd8+ Nxd8 16. e4 Ne6 17. Be3 Nd8 18. Rfe1 Re5 19. f4 Ra5 20. a4 Ne6 21. Reb1 a6 22. Rb4 Re8 23. e5 Bxg2 24. Kxg2 f5 25. exf6 gxf6 26. Rc4 f5 27. g4 c5 28. Bf2 b5 29. gxf5 bxc4 30. fxe6 Rxe6 31. f5 Rf6 32. Bg3 Rf7 33. Bh4 Rf8 34. Be7 Rb8 35. Kf3 Kf7 36. Bd6 Rc8 37. Be5 Ke8 38. Ke4 Kd7 39. Kd5 Ke7 40. f6+ Kf7 41. Ke4 Rc6 42. h4 h5 43. Kf5 1-0
[/pgn]
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