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Stockfish evaluates this as advantageous for White (+0.6 at depth 22), with Bxe4 being the only move retaining the advantage. Why is this so good for White?

  1. We give up the bishop pair
  2. We're left with the bad bishop vs the opponent's good bishop

Even after 1. Bxe4 Qxe4 2. Qxe4 dxe4 which looks like a textbook good bishop vs bad bishop scenario, Stockfish thinks that White is better (+0.2). Why is Bxe4 the best move and why does it lead to an advantage for White?

    [FEN "r3q1k1/ppb2p1p/2p3p1/2Pp1B2/1P1Pn3/4B3/P1Q2PPP/4R1K1 w - - 0 1"]
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  • Technically, The dark-squared Bishop for White isn't "bad," it's only slightly worse. And the exchange of queens lessens that. Taking your line further with Bh6, for example, with the intention of playing against the loose pawn with f3 highlights how much stronger that bishop can become.
    – Arlen
    Commented Aug 20, 2022 at 21:03

2 Answers 2

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We can't read the engine's mind. The evaluation is the result of calculation to depth 22, i.e. looking 11 moves ahead; the main line(s) after both 1 Bxe4 and White's alternatives should give some idea of why the engine gives White +0.6 here and why the alternatives (mainly Bg4 and Bh3) are worse.

Looking at it without an engine, we might guess that after the trades on e4 White has a worse Bishop but more space and a Queenside majority -- and no more worries about a Black attack on the Kingside. After 1 Bxe4 Qxe4 2 Qxe4 dxe4 White can move the Bishop outside the pawn chain with tempo (discovered attack on bPe4), and 3 Bg5 also controls d8 so that after Black defends the pawn White can continue 4 Rd1 and 5 d5, curing the d5-hole (White doesn't want to see Black play Rd5 or Kd5), start getting the Queenside pawns moving, and maybe use the d-file. White also has the option of not trading Queens and instead trying to use the e-file with something like Qd1 (Black won't play Re8 because then Bd2 wins).

If Black answers 1 Bxe4 with dxe4 then White seems to win the e-pawn by moving the Bishop (2 . . . f5 doesn't help Black because 3 f3 and the pinned pawn falls); then the "+0.6" might mean that Black has some compensation thanks to the better Bishop.

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  • 2
    "We can't read the engine's mind" - in some cases I'd agree, but more often than not it's possible to understand why the engine likes one move over another. It just takes a bit of digging and analysis. Commented Aug 17, 2022 at 2:09
  • 2
    Well if you have Stockfish then sometimes it "just takes a bit of digging and analysis" to get some sense of its reasoning by having it show you its main lines and ask about alternatives that seem promising. Without an engine, most of us can't confidently analyze a position like this out to depth 22. Commented Aug 17, 2022 at 2:54
  • No that's what I meant, digging with an engine to help you understand said engine. A person trying to understand Stockfish's moves on their own is often gonna have a bad time. Commented Aug 17, 2022 at 5:08
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Bxe4 does not lead to a permanent advantage for white, but Bg4 or Bh3 also do not.

The position is static (blocked center pawns, no passers, one open file) and the bishops are not that good in such positions. The Ne4 is as good as the Bf5. After Bxe4 Qxe4 Qc3 white has a bit more due to the control of the e-file (which is based on quite abstract tactics) and due to his qualitative majority on the queen side. His heavy pieces are more active. But black can neutralize this with careful play.

I am pretty sure that many GMs would actually avoid Bxe4 and play Bh3 or Bg4 instead, so you are right if you are doubtful about Stockfish's suggestion. All three moves, Bg4, Bh3 and Bxe4 are playable and of comparable quality. And none of them gives white a relevant advantage.

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  • 1.e4 also does not lead to a permanent advantage for White. Still, engines and humans prefer White, even though with best play, the advantage will disappear completely. Any advantage will, with best play, eventually either lead to equality or checkmate.
    – Hauptideal
    Commented Aug 19, 2022 at 17:03
  • What are these abstract tactics? Why has White the qualitative majority / what are Black's weaknesses - or do you hint at a space advantage? Why would we need to take on e4 in order to have the qualitative majority and more active major pieces?
    – Hauptideal
    Commented Aug 19, 2022 at 17:07
  • dxe4 gives White the majority (4 vs 3).
    – Arlen
    Commented Aug 20, 2022 at 21:06
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    With quite abstract tactics I mean that after 1.Bxe4 Qxe4 2.Qc3 black can not easily bring his rook to the e-file (eg. 2...Re8? 3.Bd2 +-) and it also does not work to prepare it with 2...Kf8 due to later Bh6+ ideas and also not with 2...f6, idea 3...Kf7, due to 3.Bd2 Qf5 4.Qe3 Qd7 5.Qe7 Qxe7 6.Rxe7 Rc8 and the white pieces are too active. Commented Aug 21, 2022 at 1:00
  • 1
    A long example line how to play it right after 1.Bxe4 Qxe4 2.Qc3 is 2...h5! (some space for the king, though 2...Qg4 probably also draws) 3.Bd2 Qg4! (keeps pressure on d4) 4.h3 Qd7 5.Qe3 a5! (tries to activate the rook via the a-file) 6.Qe7 Qxe7 7.Rxe7 Rc8 (looks passive but black has the time to chase away the rook) 8.bxa5 Kf8 9.Re1 Ra8 (The rook is free and goes back to the a-file) 10.Bh6+ Kg8 11.Rb1 (pressure against b7) Bxa5! 12.Rxb7 Bc3 (pressure against d4) 13.Be3 Rxa2 14.Rb3 Ba1! 15.Rb6 Ra4 = Commented Aug 21, 2022 at 1:28

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