user34039: In a 2001 book by Karsten Muller and Frank Lampart FUNDAMENTAL chess ending the following position WHITE King on a4 Bishop on d5 pawns on a5 c6 e2 BLACK King on c7 Bishop on d4 pawn on f4 WHITE to move is given as a draw. Stockfish 14.1 NNUE disagree and found a very complicated way to win for White. The position appeared in the game Alexandrov vs Gleizerov in 1993 . What do you think?
[Title "Alexandrov-Gleizerov 1993, White to move: is it really a draw?"]
[FEN "8/2k5/2P5/P2B4/K2b1p2/8/4P3/8 w - - 0 0"]

Here's a continuation Stockfish gave :
[FEN "8/2k5/2P5/P2B4/K2b1p2/8/4P3/8 w - - 0 1"]

1. Kb4 Kd6 2. Kc4 Bf2 3. Kb5 Bg1 4. Bb3 Be3 5. Ba4 Bd4 6. Kc4 Bg1 7. Bb5 Ba7 8. a6 Bb8 9. Kd4 Kc7 10. Ke5 Kb6+ 11. Kf5 Bd6 12. Ke6 Bb8 13. Kd7 Kxb5 14. a7 Bxa7 15. c7 f3 16. exf3 Kc5 17. Ke6 Kd4 18. f4 Bb6 19. c8=Q Bc5 20. f5 Ba3 *


user33803: There are quite a number of lines here, and it's not obvious how White can force concessions. In sum, White must either win f4, win a bishop for a pawn, or trade their c- for Black's f-pawn. I'll elaborate on the non-obvious latter.
Tablebase observation: First, note that your position without e+f is a tablebase draw:
[fen "8/2k5/2P5/P2B4/K2b4/8/8/8 w - - 0 1"]

Your position without a+f is also a tablebase draw:
[fen "8/2k5/2P5/3B4/K2b4/8/4P3/8 w - - 0 1"]

But your position without c+f is a tablebase win:
[fen "8/2k5/8/P2B4/K2b4/8/4P3/8 w - - 0 1"]

Summary: Black can defend against a+c as well as against c+e, but is lost against a+e.
Conclusion: White's general plan is thus to trade their c- for Black's f-pawn. They seek to send Black's bishop to b8, from where it eyes both f4 and the critical a7, but remains moveless. Then the manoevre c7+-Kxc7-Kxf4 can be prepared and exerted as shown, leading into a known tablebase win.
[fen "1bk5/8/2P5/P2B1K2/5p2/8/4P3/8 w - - 0 1"]

1. Be4 Bc7 2. a6 Bb8 3. Bd3 Kd8 4. c7+ Kxc7 5. Kxf4

TLDR: Keep your outside pawns and seek to trade c- and f-pawn.

34039: <p>In a 2001 book by Karsten Muller and Frank Lampart FUNDAMENTAL chess ending the following position WHITE King on a4 Bishop on d5 pawns on a5 c6 e2 BLACK King on c7 Bishop on d4 pawn on f4 WHITE to move is given as a draw. Stockfish 14.1 NNUE disagree and found a very complicated way to win for White. The position appeared in the game Alexandrov vs Gleizerov in 1993 . What do you think?</p>
<pre><code>[Title &quot;Alexandrov-Gleizerov 1993, White to move: is it really a draw?&quot;]
[FEN &quot;8/2k5/2P5/P2B4/K2b1p2/8/4P3/8 w - - 0 0&quot;]
</code></pre>
<p>Here's a continuation Stockfish gave :</p>
<pre><code>[FEN &quot;8/2k5/2P5/P2B4/K2b1p2/8/4P3/8 w - - 0 1&quot;]

1. Kb4 Kd6 2. Kc4 Bf2 3. Kb5 Bg1 4. Bb3 Be3 5. Ba4 Bd4 6. Kc4 Bg1 7. Bb5 Ba7 8. a6 Bb8 9. Kd4 Kc7 10. Ke5 Kb6+ 11. Kf5 Bd6 12. Ke6 Bb8 13. Kd7 Kxb5 14. a7 Bxa7 15. c7 f3 16. exf3 Kc5 17. Ke6 Kd4 18. f4 Bb6 19. c8=Q Bc5 20. f5 Ba3 *
</code></pre>
 33803: <p>There are quite a number of lines here, and it's not obvious how White can force concessions. In sum, White must either win f4, win a bishop for a pawn, or trade their c- for Black's f-pawn. I'll elaborate on the non-obvious latter.</p>
<p><strong>Tablebase observation</strong>: First, note that your <em>position without e+f</em> is a <a href="https://syzygy-tables.info/?fen=8/2k5/2P5/P2B4/K2b4/8/8/8_w_-_-_0_1" rel="noreferrer">tablebase</a> draw:</p>
<pre><code>[fen &quot;8/2k5/2P5/P2B4/K2b4/8/8/8 w - - 0 1&quot;]
</code></pre>
<p>Your <em>position without a+f</em> is also a <a href="https://syzygy-tables.info/?fen=8/2k5/2P5/3B4/K2b4/8/4P3/8_w_-_-_0_1" rel="noreferrer">tablebase</a> draw:</p>
<pre><code>[fen &quot;8/2k5/2P5/3B4/K2b4/8/4P3/8 w - - 0 1&quot;]
</code></pre>
<p>But your <em>position without c+f</em> is a <a href="https://syzygy-tables.info/?fen=8/2k5/8/P2B4/K2b4/8/4P3/8_w_-_-_0_1" rel="noreferrer">tablebase</a> win:</p>
<pre><code>[fen &quot;8/2k5/8/P2B4/K2b4/8/4P3/8 w - - 0 1&quot;]
</code></pre>
<p><strong>Summary</strong>: Black can defend against a+c as well as against c+e, but is lost against a+e.</p>
<p><strong>Conclusion</strong>: White's general plan is thus to trade their c- for Black's f-pawn. They seek to send Black's bishop to b8, from where it eyes both f4 and the critical a7, but remains moveless. Then the manoevre c7+-Kxc7-Kxf4 can be prepared and exerted as shown, leading into a known tablebase win.</p>
<pre><code>[fen &quot;1bk5/8/2P5/P2B1K2/5p2/8/4P3/8 w - - 0 1&quot;]

1. Be4 Bc7 2. a6 Bb8 3. Bd3 Kd8 4. c7+ Kxc7 5. Kxf4
</code></pre>
<p><strong>TLDR</strong>: Keep your outside pawns and seek to trade c- and f-pawn.</p>
