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When reviewing my games on Lichess, I very often find the Lichess engine recommending to me to sacrifice the bishop early on after checking the enemy king. I have created a sample game where you can see it happening. I don't see myself in any better position there, so I am curious what I gain by doing this.

[FEN ""]

1. e4 c5 2. Nf3 Nc6 3. c4 Nd4 4. Nxd4 cxd4 5. d3 e5 6. Be2 Bb4+ 7. Bd2 Bxd2+ 8. Qxd2

I just don't understand why it wants me to move my bishop to b4 in the first place. I'd much rather want to develop my position more by doing c5 or knight f6 or similar.

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    Engines are good for analyzing tricky tactical lines in openings, but trying to gain insight into opening positions that are more strategic in nature is not a good use of Stockfish. The engine will tell you which move scores best in its algorithm. Sometimes there are good strategic reasons for it. Sometimes it is a move that humans would rarely want to play. Sometimes it is a good move, but only if you understand how to use it. Sometimes it is barely better for the move that feels more natural to you. – Eric Wilson Oct 6 '20 at 1:20
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    If you retreat, then all you did was let white develop the bishop for free. There's not a good way to defend the bishop, and if you retreat, then white has gained a tempo, you could have played 5 ...Be7 6. Bd2, and it'd be your turn. So in general, it doesn't look like a good move to begin with, and either you trade and you keep tempo, or you retreat to a position you could have gone to in the first place. – Issel Oct 6 '20 at 16:46
  • Thanks everyone for all the great input, especially for all the helpful edits to make my question more clear. This is definitely one of the best stackexchanges I've participated in. – Xatenev Oct 6 '20 at 19:39
  • Maybe everybody is thinking too deeply here. When you are ahead in material, exchange pieces. If white moves the king out of check instead of Bd2, white's development is going nowhere fast and black has pretty much the whole board to choose from. – alephzero Oct 6 '20 at 20:12
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I wouldn't say it was a "sacrifice", it was more like an exchange of bishops.

My lichess engine was actually giving me ...Bd6 as the first move.

I don't understand why it wants me to move my bishop to b4 in the first place

Me neither. I doubt anyone here will have an idea. Stockfish doesn't tell us why. If I have to make a guess, I would say the bishop is being blocked by the d4-e5 pawn chain, so it makes sense to exchange the bad bishop off.

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  • I see, that makes sense. So I am essentially just swapping my bishop in a bad position for his free bishop that has a lot more space. Thank you – Xatenev Oct 5 '20 at 15:11
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    6...Bd6 7.O-O Ne7 8.f4 exf4 9.Bxf4 Bxf4 10.Rxf4 does not look very good for Black – B.Swan Oct 5 '20 at 18:12
  • @B.Swan I don't know, but that's not point of the question. – SmallChess Oct 5 '20 at 18:14
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    @SmallChess, I think he is saying that it could be a factor for why stockfish recommended that. – fartgeek Oct 5 '20 at 23:11
  • Can't you see what situation the engine thinks it will end up in (the PV) and compare that to what would happen after the second best move? – JollyJoker Oct 6 '20 at 14:20
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Once white has put pawns on the central white squares of d3, c4 and e4 his white squared bishop becomes very bad, because its mobility is drastically reduced, and his dark squared bishop becomes essential for protecting the dark squares that have become weak thanks to the pawn moves.

That means that 7.Bd2 is a blunder because it allows black to exchange the dark squared bishops leaving white with a bad position. Much better would have been 7.Nd2 followed by a3 and b4 to chase the dark squared bishop away.

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    Blunder sounds like strong language for the move. Maybe a mistake – Cruncher Oct 6 '20 at 15:33
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Mostly when the engine suggests a such exchange maneuverer it means that either your piece has no future, or the blocking piece has a very good future. Since you need to move the bishop somewhere to get castled, it chooses to exchange it off.

If you look for plans in the variation you given, the most natural way for White to proceed is to break in the center with f4 at some point, where you can support your center with ...d6. The bishop would find it hard to find a meaningful role in this structure.

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There isn't a sacrifice in the line you gave. I assume you man 6...Bb4+.

The bishop is a bad bishop because it's blocked by its own pawns in the center. 7.Bd2 is virtually forced trading black's bad bishop for white's good bishop. The alternatives for white just aren't very good.

It also frees up black's position because he can play d6 to develop the other bishop and he has Ne7 as an option too.

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That is not a sacrifice at all. It is an exchange. You get rid of a bad bishop for his better one. It is positional play for a very minor advantage. But still an advantage. Enough small ones add up to be enough to win material and the game.

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Three Options

After 7.Bd2 Black has three options:

Retreat: Black can pull the dark bishop back. Retreating to c5 doesn't work, since White can just push the b pawn forward, and force the dark bishop to retreat again, so you'd have to go back to d6 or further. The issue with this is tempo - you've giving white a free turn to develop.

Defend: You can try to use your Queen or the a pawn to defend the bishop, but these are a little awkward. In the pawn's case, White can exchange for the bishop anyway, and you are left with doubled pawns on b, and now you have to defend the forward pawn or just coincide it. The Queen defense line is more complex, and I'm not sure I'm experienced enough to do it justice. Bottom line is, your Queen is either tied down defending that bishop, since you can't get any other support there easily, or White is going to exchange for the bishop (again) and either push your Queen around or try to exchange for it.

Exchange: Or exchange for the bishop. Your example ends with White's Queen taking the dark bishop. This doesn't really develop White's Queen, so you gain tempo by following it up with a development move - maybe the knight f6 you mention in your question.

Bottom line: the bishop is probably going to be exchanged, so you might as well do it in a way that doesn't give White anything. Moving the White Queen one square forward isn't much in the way of development, so that seems a good exchange.

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