Fortress here? Plus a bonus zugzwang.

[Ajedrecista]

Hello:

I played other interesting-to-me 5+0 blitz game today that led to a R+B+P vs. Q imbalance. I was white:

[pgn][Event ""]
[Site ""]
[Round ""]
[Date "2026.01.14"]
[Result "1-0"]

1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. Nc3 Bb4 { D38 Queen's Gambit Declined: Ragozin Defense } 5. Qb3 Nc6 6. e3 O-O 7. a3 Bd6 8. cxd5 exd5 9. Bd2 Re8 10. Nxd5 Nxd5 11. Qxd5 Rxe3+ 12. fxe3 Bg3+ 13. hxg3 Qxd5 14. Bd3 Bg4 15. Bxh7+ Kf8 16. Kf2 g6 17. Rh4 Bxf3 18. gxf3 Kg7 19. Bc3 Rh8 20. e4 Qb3 21. d5+ Ne5 22. Bxe5+ f6 23. Bc3 Qc2+ 24. Ke3 Rxh7 25. Rxh7+ Kxh7 26. Rh1+ Kg7 27. Re1 Qg2 28. g4 g5 29. Re2 Qg3 30. Re1 Qf4+ 31. Kf2 Kg6 32. Re2 b5 33. Re1 Qh2+ 34. Ke3 Qd6 35. Kf2 c6 36. dxc6 Qxc6 37. Ke3 Qc5+ 38. Ke2 Qb6 39. Kf1 a5 40. Ke2 b4 41. axb4 axb4 42. Bd2 { White wins on time. } 1-0[/pgn]

After 39.- ..., a5 (0.00 evals), I played 40.- Ke2 in time trouble, which SF does not like at all. The next few moves in the game were the top choices for SF until my opponent flagged. Is there a fortress here?

[d]8/8/1q3pk1/pp4p1/4P1P1/P1B2P2/1P2K3/4R3 b - - 1 40

SF recommends 40.- ..., b4; 41.- axb4, axb4; 42.- Bd2, Qd4; 43.- Bc1 and I do not see progress after that, with white moving the rook through the first rank and the king not far away of the f3-pawn. Black just shuffles the queen and king, despite -1, -1.2 evals or so. There are other choices for black's 42nd move, but I see the same. Am I missing something? Thanks in advance.

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I add a bonus zugzwang of other game that I played today, this time easily won by me (something like K vs. K+4P, with me being black). I discovered a curious pattern that I wanted to share with a made-up example: white to play and draw or black to play and lose:

6k1/8/5P1P/8/8/6p1/6Pb/7K w - - 0 1
6k1/8/5P1P/8/8/6p1/6Pb/7K b - - 0 1

White to move can only move f7+ or h7+, with the black king capturing that pawn; then white advances the other pawn, black king moves to g7; white promotes or underpromotes and black captures, ending in a stalemate.

Black to move unveils the pattern and lose. Focusing on the black king's rook corner:

Code: Select all

▓▓▓ Square covered by white f-pawn.
░░░ Square covered by white h-pawn.

 1.- ..., Kf7           1.- ..., Kh7
 2.-  h7                2.-  f7

  f   g   h              f   g   h
+---+---+---+          +---+---+---+
|   |░░░|   | 8        |   |▓▓▓|   | 8
+---+---+---+          +---+---+---+
| k |▓▓▓| P | 7        | P |░░░| k | 7
+---+---+---+          +---+---+---+
| P |   |   | 6        |   |   | P | 6
+---+---+---+          +---+---+---+

With either sequence, the black king can not return to the g-file to stop white queening! I am sure I did not discover anything new, just discovered it by myself, but looked curious to me and wanted to share; it was a curious pattern like the following very well-known tactic dribbling pawns:

8/ppp5/8/PPP5/1k6/8/8/7K w - - 0 1

1.- b6, axb6; 2.- c6, bxc6; 3.- a6 (1-0)
1.- b6, cxb6; 2.- a6, bxa6; 3.- c6 (1-0)

Similar to YACPDB #357888 if black firstly moves the king.

Regards from Spain.

Ajedrecista.

[cc2150dx]

After 22 billion nodes:

FEN: 8/8/1q3pk1/pp4p1/4P1P1/P1B2P2/1P2K3/4R3 b - - 1 40

Stockfish-windows-x86-64-avx2: (latest development version)

85/131 36:48 22,537,114k 10,205k -0.05 1. ... b4 2.axb4 axb4 3.Bd2 Qd4 4.Bc1 Qe5 5.Ke3 Qc5+ 6.Kd3 Kf7 7.Be3 Qb5+ 8.Kd2 Qe5 9.Kc2 Qe6 10.Bc1 Qc6+ 11.Kd2 Qd6+ 12.Ke2 Qc5 13.Kd1 Qd4+ 14.Ke2 Ke6 15.Kf1 Qc4+ 16.Kf2 Qc2+ 17.Kg3 Kd6 18.Rf1 Kc6 19.Re1 Kc7 20.Rh1 Qe2 21.Rh7+ Kd6 22.Rh1 Kc6 23.Rg1 b3 24.Rh1 Kc5 25.Rg1 Kc4 26.Rh1 Kd4 27.Rg1 Kd3 28.Rh1 Kc4 29.Rg1 Qc2 30.Rh1 Kd4 31.Re1 Ke5 32.Rg1 Qe2 33.Rh1 Ke6 34.Rg1 Kd6 35.Rh1 Kd7 36.Rh7+ Ke8 37.Rh1 Kf7 38.Rh7+ Kg8 39.Rh1 Kg7 40.Rg1 Kf8 41.Rh1 Ke7 42.Rg1 Kd7 43.Rh1 Kc6 44.Rg1 Kc5 45.Rh1 Kb6 46.Rg1 Kb5

[Jouni]

This is weird position. Some engines think first black has huge advantage

Analysis by Reckless 0.9.0-dev-2a847427:
...
40...b4 41.axb4 axb4 42.Bd2 Qd4 43.Bc1 Kf7 44.Kf1 Qd3+ 45.Kg2 Qc2+ 46.Kg3 Kg6 47.Rf1 Kg7 48.Re1 Kf7 49.Rh1 Qe2 50.Rh7+ Kg6 51.Rh1 Kg7 52.Rg1 Kf7 53.Rh1 Ke6 54.Rg1 b3 55.Rh1 Kf7 56.Rh7+ Kg6 57.Rc7 Qf1 58.Rc8
-+ (-3.54) Depth: 25/63 00:00:07 48971kN, tb=70463
...

[Ajedrecista]

Hello:

This is weird position. [...]

Weird, but real! This happens when chess is playing by others than GMs at classical time controls. Something like when (association) football is played by others than Pelé, Di Stéfano...

https://x.com/Crap90sFootball (Short videos of outraging football blunders).

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

[...] Some engines think first black has huge advantage

Analysis by Reckless 0.9.0-dev-2a847427:
...
40...b4 41.axb4 axb4 42.Bd2 Qd4 43.Bc1 Kf7 44.Kf1 Qd3+ 45.Kg2 Qc2+ 46.Kg3 Kg6 47.Rf1 Kg7 48.Re1 Kf7 49.Rh1 Qe2 50.Rh7+ Kg6 51.Rh1 Kg7 52.Rg1 Kf7 53.Rh1 Ke6 54.Rg1 b3 55.Rh1 Kf7 56.Rh7+ Kg6 57.Rc7 Qf1 58.Rc8
-+ (-3.54) Depth: 25/63 00:00:07 48971kN, tb=70463
...

This is the reason why I opened a thread: high evals without apparent progress. Once again, a no-name fooling the biggest names!

Regards from Spain.

Ajedrecista.