Answers.Body: <p>Contrarily to all what was said here (including the deleted post), if Black can win, then with the immediate 1...a5! 2.bxa5 Kd3! Principle of different-color bishop endgames: you need two passers far away to &quot;scissor&quot; the opponent bishop. Note that a) the Bc6 holds the a- and c- pawn AND protects the f-passer (after f3), good boy and b) the bishop can't defend a3 since it doesn't reach b4 in time (assuming Pf3: Bc1 Kc2 Be3 Kb2). And Pf3 and Pb4 are too far apart.</p>
  <p>But that's not the end of the story, as White can try 1...a5 2.Ke2 (now or never) f3+ 3.Kd2. Then Black wins with a4. The king penetrates via b3, as White can't bring the B to f2 in time AND block the bK out with Kc3. Timing is crucial in this endgame, I've got a hunch that already Ph6/Ph7 instead of Pg5/Pg6 saves White's hide.</p>
  <p>Don't take this analysis for granted, I'm an endgame god :-) but alas, no engine (and used none). But even with one minute left, I would have played a5!</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-03-03T18:55:29.610Z
Answers.Text: The bishop can't reach b4, but the engine finds a way to defend the pawn anyways: After 3. Be5 f3 4. a6 Kc4 5. a7 Kb3, it uncorks 6. Bd6!. Now if Kxa3, 7. a8=Q+ Bxa8 8. c6+! (this discovered check cuts off the bishop's defense of f3) b4 9. Kxf3 Bxc6+ 10. Ke3 and white can reach the pawn in time to stop promotion. Still probably the better practical option since white may miss that tactic.
Answers.UserDisplayName: eyeballfrog
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Answers.CreationDate: 2023-03-03T19:33:56.957Z
Answers.Text: Aha! Had an analog idea with Bb6, to play c6 as soon as the Bc6 can be forced to move (for helping invasion), but it seemed it wasn't needed. Neat trick.
Answers.UserDisplayName: Hauke Reddmann
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-03-01T09:00:42.897Z
Answers.LastActivityDate: 2023-03-01T09:00:42.897Z
Answers.UserDisplayName: Hauke Reddmann
Body: <p>In the position below Minic just had to play one move to reach the time control and, in those days, the adjournment which would have given his team a chance to find the win. Unfortunately he blundered with Bd5 and the win was gone and the game was agreed drawn without resuming.</p>
  <pre><code>[fen &quot;&quot;]
  [Title &quot;Bellon - Minic, Siegen Olympiad 1970&quot;]
  [Startply &quot;79&quot;]
  
  1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Bc4 e6 7.Bb3 b5 8.O-O Be7 9.f4 O-O 10.a3 Bb7 11.Qf3 Nbd7 12.Re1 Rc8 13.g4 Rxc3 14.bxc3 Nc5 15.g5 Nfxe4 16.Qh5 Qc8 17.Re3 g6 18.Qh3 e5 19.Qxc8 Rxc8 20.fxe5 dxe5 21.Nf3 Nxb3 22.cxb3 Bc5 23.Nxe5 Nxg5 24.Kf1 Bxe3 25.Bxe3 Ne6 26.c4 f6 27.Nd7 f5 28.c5 f4 29.Bf2 Rd8 30.Rd1 Bc6 31.Nf6+ Kf7 32.Rxd8 Nxd8 33.Nxh7 Ne6 34.h4 Kg7 35.Ng5 Nxg5 36.hxg5 Kf7 37.Bd4 Ke6 38.b4 Kd5 39.Bf6 Ke4 40.Kf2 Bd5 1/2-1/2
  </code></pre>
  <p>I could ask how does black win from the position after white's 40th move but you would all just plug the position into your engines. So, instead:</p>
  <p>Why was Bd5 a blunder? How did it give his opponent a chance to save the draw.</p>
  <p><strong>Hint</strong>: This question is based on analysis by Artur Jusupov in a Chess24 video a few years ago. Freedom of movement is more important than material.</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2023-02-25T09:22:37.297Z
Comments.Text: The only reason I could imagine is that White sacrifices a pawn with c6 to enable to help the bishop to defend the queenside, but the position still seems to be lost. I could not find a crucial difference. The engine (at least mine) seems also not to be able to find it out
Comments.UserDisplayName: Peter
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2023-03-01T10:48:01.203Z
Comments.Text: @user30536 Done
Comments.UserDisplayName: Brian Towers
Tags: <analysis><endgame><puzzles>
Title: Black to play and win but why was the move played a blunder?
ThreadText: # Black to play and win but why was the move played a blunder?
  
  (Asked by: username_0 on 2023-02-11)
  
  In the position below Minic just had to play one move to reach the time control and, in those days, the adjournment which would have given his team a chance to find the win. Unfortunately he blundered with Bd5 and the win was gone and the game was agreed drawn without resuming.
  
  ```
  [fen ""]
  [Title "Bellon - Minic, Siegen Olympiad 1970"]
  [Startply "79"]
  
  1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Bc4 e6 7.Bb3 b5 8.O-O Be7 9.f4 O-O 10.a3 Bb7 11.Qf3 Nbd7 12.Re1 Rc8 13.g4 Rxc3 14.bxc3 Nc5 15.g5 Nfxe4 16.Qh5 Qc8 17.Re3 g6 18.Qh3 e5 19.Qxc8 Rxc8 20.fxe5 dxe5 21.Nf3 Nxb3 22.cxb3 Bc5 23.Nxe5 Nxg5 24.Kf1 Bxe3 25.Bxe3 Ne6 26.c4 f6 27.Nd7 f5 28.c5 f4 29.Bf2 Rd8 30.Rd1 Bc6 31.Nf6+ Kf7 32.Rxd8 Nxd8 33.Nxh7 Ne6 34.h4 Kg7 35.Ng5 Nxg5 36.hxg5 Kf7 37.Bd4 Ke6 38.b4 Kd5 39.Bf6 Ke4 40.Kf2 Bd5 1/2-1/2
  
  ```
  
  I could ask how does black win from the position after white's 40th move but you would all just plug the position into your engines. So, instead:
  
  Why was Bd5 a blunder? How did it give his opponent a chance to save the draw.
  
  **Hint**: This question is based on analysis by Artur Jusupov in a Chess24 video a few years ago. Freedom of movement is more important than material.
  
  **Tags:** analysis, endgame, puzzles
  
  > **Comments:**
  > **username_1**: The only reason I could imagine is that White sacrifices a pawn with c6 to enable to help the bishop to defend the queenside, but the position still seems to be lost. I could not find a crucial difference. The engine (at least mine) seems also not to be able to find it out  
  > **username_0**: @user30536 Done  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_2 on 2023-03-01. Score: 3
  
  Contrarily to all what was said here (including the deleted post), if Black can win, then with the immediate 1...a5! 2.bxa5 Kd3! Principle of different-color bishop endgames: you need two passers far away to "scissor" the opponent bishop. Note that a) the Bc6 holds the a- and c- pawn AND protects the f-passer (after f3), good boy and b) the bishop can't defend a3 since it doesn't reach b4 in time (assuming Pf3: Bc1 Kc2 Be3 Kb2). And Pf3 and Pb4 are too far apart.
  
  But that's not the end of the story, as White can try 1...a5 2.Ke2 (now or never) f3+ 3.Kd2. Then Black wins with a4. The king penetrates via b3, as White can't bring the B to f2 in time AND block the bK out with Kc3. Timing is crucial in this endgame, I've got a hunch that already Ph6/Ph7 instead of Pg5/Pg6 saves White's hide.
  
  Don't take this analysis for granted, I'm an endgame god :-) but alas, no engine (and used none). But even with one minute left, I would have played a5!
  
  > **Comments:**
  > **username_3**: The bishop can't reach b4, but the engine finds a way to defend the pawn anyways: After 3. Be5 f3 4. a6 Kc4 5. a7 Kb3, it uncorks 6. Bd6!. Now if Kxa3, 7. a8=Q+ Bxa8 8. c6+! (this discovered check cuts off the bishop's defense of f3) b4 9. Kxf3 Bxc6+ 10. Ke3 and white can reach the pawn in time to stop promotion. Still probably the better practical option since white may miss that tactic.  
  > **username_2**: Aha! Had an analog idea with Bb6, to play c6 as soon as the Bc6 can be forced to move (for helping invasion), but it seemed it wasn't needed. Neat trick.  
  
  ---
  
  