It is all Positional
I would like to talk about exchanges as a means to achieve some strategic objective. The first objective that I want to concentrate on here is to exchange in order to get an open file. An open file is a powerful weapon; the side that has the file can use it to penetrate the opponent’s position, 7th rank, attack weaknesses, etc. The second strategic objective that I want to talk about is exchanging a piece that covers weak squares. If one side has a complex of weak squares, the other side can use it only if they eliminate the defenders. The third strategic goal that will be presented here is to exchange an active piece of the opponent's that holds his position together. After this exchange the position that was holdable before would collapse. And the last point in this article is to exchange pieces in order to underline one piece that is placed badly. The side with a badly placed piece, usually on one of the flanks will not be able to defend the other flank, where the opponent will start his attack.
Exchange in order to open a file.
An open file is an advantage if we control it and a disadvantage when the opponent controls it. Thus, when opening a file one has to be very careful in judging who would be the first one to occupy the file. Rooks are the best pieces to take over the file, the queen can be good too. Also, if there are no good squares to penetrate the opponent’s position, controlling an open file might be a useless task. If one weighs all these pros and cons and decides that having an open file benefits him, then he should go for the piece exchange that leads to this.
White is better because his king is safer and he has more space. Black’s king occupies an unsafe position if one takes into consideration the pawn on f5. So far the position is closed and one cannot feel the defects of black’s position.
A weak complex of squares usually occurs when one side places his kingside or queenside pawns on the same color, thus leaving the other color undefended by pawns. The opponent should strive to use these weaknesses. If there are as many defenders as attackers then it is hard to achieve something. Usually, the strategy is to exchange knights, because they can defend either black or white squares. Then, to exchange the bishop that is the same color as the weak squares are, leaving the bishop which cannot defend the weak squares. It is favorable for the attacking side to have a knight to exploit the weak squares of the opponent, or the bishop of the same color as the opponent’s weak complex.
Exchanging the only active piece that holds the position together.
Sometimes, the opponent’s position has many weaknesses and only one defender. This is usually the most active piece that manages to multitask. By exchanging it, suddenly it is impossible to defend all the weaknesses at once.
Black was unable to solve their opening problems: Nb6 is misplaced, Bc8 and the rooks are not developed. White has full control of the d-file because of doubled rooks. If white manages to push a5, b6 would be a permanent weakness as well as b7, while e5 is already a weakness. White finds a way to use all his advantages, while exploiting black’s disadvantages.
Exchange to underline a badly placed piece.
There are positions where one side has a badly placed piece. We would try to play around it, to attack on the opposite wing, so that the opponent would not be able to bring this piece into the defense. At the end, he might manage to bring it into play but it is usually too late.
Black’s main disadvantage is the Na5. It has no prospects, if black tries to transfer it through b6-Nb7-Nd6, this will open the diagonal for Bg2. White’s strategy is quite simple: to exchange all the pieces and leave Na5.
Overall, the exchange is a powerful positional weapon. When one strives to get to a positional objective, exchange of pieces can be a good means to achieve it. I only looked briefly at four positional exchanges. There are many more. If the readers request I can go into greater depth on one of these positional exchanges.
