Glossary of Chess Problems - D

D

Directmate

A type of problem where white, moving first, is required to checkmate black in a specified number of moves against any defence. Such a problem is usually indicated by the stipulation "mate in two" (or however many moves is necessary) or "checkmate in two". The term directmate is useful to distinguish these sorts of problems from helpmates, selfmates, reflexmates and others.

Domination

In studies, a situation whereby a piece has relatively wide freedom of movement but which nevertheless must be lost.

Doubling

A manoeuvre in which two pieces are placed on the same line (rank, file or diagonal) such that they support each other. Special cases are Turton doubling and Zepler doubling.

Dual

Ideally, white should have only one move at each juncture which solves a problem - if white has an alternative at any stage other than the first move, this is a dual. A dual is not as serious a flaw as a cook, and in minor lines, duals may be permissible (opinions differ on this point). Some problems make a virtue out of dual avoidance - of two apparently equivalent white moves, only one works.

Duplex

A type of problem in which there are two solutions, the second one reversing the roles of the colours in the first. The most common type is the duplex helpmate, in which the two solutions to be found are: black moves first and cooperates with white to be mated; and white moves first and cooperates with black to be mated.