The Exchange (chess) - Minor Exchange

The minor exchange refers to the capture of the opponent's bishop for the player's knight (or, more recently, the stronger minor piece for the weaker) (Soltis 2004:169). Bobby Fischer used the term (Benko 2007:192,199,216), but it is rarely used.

In most chess positions, a bishop is worth slightly more than a knight because of its longer range of movement. As a chess game progresses, pawns tend to get traded, removing support points from the knight and opening up lines for the bishop. This generally leads to the bishop's advantage increasing over time.

Traditional chess theory espoused by masters such as Wilhelm Steinitz and Siegbert Tarrasch puts more value on the bishop than the knight. In contrast, the hypermodern school favored the knight over the bishop. Modern theory is that it depends on the position, but that there are more positions where the bishop is better than where the knight is better (Mayer 1997:7).

There are some occasions when a knight can be worth more than a bishop, so this exchange is not necessarily made at every opportunity to do so.

A rook and bishop usually work better together than a rook and knight in the endgame (Mayer 1997:201–8), (Beliavsky & Mikhalchishin 2000:141). José Raúl Capablanca stated that a queen and knight work better together than a queen and bishop in the endgame (Mayer 1997:209–18). More recently, John Watson has stated that from his study of this endgame that an unusually large proportion of queen and knight versus queen and bishop endings are drawn, and that most decisive games are characterized by the winning side having one or more obvious advantages (for example, having a knight against a bad bishop in a closed position, or having a bishop in a position with pawns on both sides of the board, particularly if the knight has no natural outpost). Watson states that positions in this endgame in general "are very volatile, and often the winning side is simply the one who starts out being able to win material or launch an attack on the opposing king" (Watson 1998:73). Glenn Flear agrees with that assessment for endgames. He could not find an endgame by Capablanca that supported his statement. The statistics for queen and bishop versus queen and knight endgames are about even. Most decisive games were won because of a significant advantage from the middlegame and only a limited number of positions show an inherent superiority for one over the other (Flear 2007:422).