Glossary of Chess Problems - B

B

Babson task

A problem in which black promotion defences to all possible pieces are answered by white promotions to the same piece black has promoted to. An extreme form of Allumwandlung.

Battery

A pair of pieces, where the front piece moves away to discover an attack from the back piece. For example, if a White knight stands between a White rook and the Black king, moving the knight - that is, "firing" the battery - leads to check.

Block

A problem in which the key provides no threat, but instead puts black in a position of zugzwang, where every move leads to a mate. In a complete block, all of black's moves have mates provided in the set play and the key is simply a waiting move; in an incomplete block, not all black moves are provided with mates in the set play - the key provides for those that don't; in a mutate some of the mates provided in the set play are changed following the key.

By-play

Variations not directly connected to the problem's theme.