Last week we started the bishop endgame series and will continue with this topic with the next few articles. Today's theme is bishop exchange in same-color bishop endings. After the bishops are traded a pawn endgame arises. The purpose of the trade is usually to get a winning pawn endgame for the attacking side or a drawn pawn endgame for the defending side. Since pawn endgames have definite evaluations bishop trades do not bring small or big advantage they either lead to a winning or drawing position. We will look at both cases today and also some examples where bishop trades arise in the context of more subtle ideas.
Let us warm up with these two fairly easy positions. In the first position black is up a pawn but he might face some trouble realizing it due to a backward b6-pawn. During the game he found the easiest solution to the problem by trading the bishops. In pawn endgames being a pawn up almost always guarantees a win. White cannot avoid the bishop trade because the a4-pawn would be lost.
Sometimes when the trade is offered one does not need to accept it or to move away the bishop, it is possible to keep the bishop undefended and under attack! The next example illustrates this aesthetic idea. White just offered black the bishop trade but black cannot really accept it because the bishop on b7 is poisoned. Instead, black wants to prepare a pawn march, so he questions how to do that with a tempo?
Now that we did little exercises it is time to step up to the next level. The next position is similar to example one where one can avoid the bishop trade at the cost of a pawn. The material is equal and the position is balanced. Black should not lose this position but probably he missed the bishop trade idea after which the defense in the pawn endgame becomes harder and harder.
In equal positions keeping the bishops on the board will provide some resources for a fight. Because if after the bishop trade the pawn endgame is a dead-draw, then even a very strong player can do little to win. Observe how black out of an equal position got a small plus after the pawn got to f4. Then trading the f4-pawn for white's b4-pawn ensured black a long-term advantage due to the connected a- and b-pawns. White's king had to defend the kingside pawns and also keep an eye on the far-advanced black pawns on the queenside.
In conclusion we will look at the following example, which involves intricate maneuvering with bishops for both sides. White has an advanced a-pawn that the black bishop or king has to guard. White's king is centralized and if given a chance can give a hand to the a-pawn or attack the weakness on h6. Black's position is worse but he hopes to use the weakness on g4 and the fact that the h8-square is of the opposite color to white's bishop. This means that an endgame where white only has the bishop and the h-pawn will be a draw. After white missed several winning chances, black got to use these two defensive ideas.
Today we looked at several bishop endgame examples where the idea of the bishop trade appeared. In the first and third positions the key idea was the bishop trade to transpose into a winning pawn endgame. Sometimes one can leave the bishop under attack and instead prepare pawn advances as it was done in the second example. Keeping bishops on the board avoids an immediate draw in equal endgames - the third position shows precisely this. And the final position shows the defensive potential in bishop endgames. Next week we will look at the concept of a "bad bishop".