The Key

The key is the first move of the solution of a chess composition. The key is a move by the White in all kinds of problems (Orthodox problems, Selfmate problems, Studies, etc.), except in the Helpmate problems where the key is a move by the Black.

The key must be a move which can be found with difficulty, in order to justify the determination “chess problem”.

The key must be the unique move that solves the problem. If there is some other move, (which the composer is not aware of), which also solves the problem, then the problem is considered useless and is called cooked. The exception here is those problems that deliberately have more than one solution, as it is usual in Helpmate compositions, where one solution complements the other in a prominent way. For example, solutions with same strategy (omostrategic), or solutions where two white pieces exchange roles, etc.

In all types of problems, the key is allowed to be any normal move, or capture, or promotion of a pawn, but specially:

(1) castling is allowed (king’s side castling 0-0 or queen’s side castling 0-0-0), except if it can be shown with Proof analysis that the king or the relevant rook has made a move, (thus proving that castling is illegal).

(2) en passant (e.p.) capture of a pawn is not allowed, except if it can be shown with Proof analysis that this pawn has made a two-steps move, exactly in the previous half-move.

Each move in chess can be seen as two half-moves, one by White and one by Black. In first move, the half-moves are W1 and B1. In the second move, the half-moves are W2 and B2, etc.

In the following posts we will see when a key is considered good or not, by examining some characteristics of the keys.