Queen against two rooks or three minor pieces, as well as a rook plus pawn vs two minor pieces - these are typical constellations where the material is unbalanced. In our first steps in chess we are taught about the nominal value of the pieces. The queen is equal to nine pawns; a rook to five, a minor piece is worth three pawns. This is a common sense solution aimed at teaching the beginner a system of values so that he or she does not trade a more valuable piece for a less good one. Later however, situations occur in games in which one side can trade two minor pieces (six pawns) for a rook and a pawn (also six pawns). Theoretically speaking, this should result in an equal position, but in reality one of the two sides will profit from the exchange. There are many cases of material imbalance in chess. In his new DVD GM Dejan Bojkov of Bulgaria makes an attempt to systematise the most important ones and gives valuable advice on how to handle the resulting positions. He also explains the hidden factors behind the imbalances, explanations which will guide you through the art of exchanging pieces.
And a fragment: