Pure mate

rdf:langString Pure mate

rdf:langString In chess, a pure mate is a checkmate position such that the mated king is attacked exactly once, and prevented from moving to any of the adjacent squares in its field for exactly one reason per square. Each of the squares in the mated king's field is attacked or "guarded" by one—and only one—attacking unit, or else a square which is not attacked is occupied by a friendly unit, a unit of the same color as the mated king. Some authors allow that special situations involving double check or pins may also be considered as pure mate. Pure mates are of interest to chess problem composers for their aesthetic value. In real gameplay, their occurrence is incidental. Nevertheless, several famous games have concluded with a pure mate, including the Immortal Game and the Evergreen Game—both won by Adolf Anderssen—the Peruvian Immortal, and the Game of the Century, an early brilliancy won by Bobby Fischer. Pure mate is one of a few terms used by composers to describe the properties of a checkmate position; related concepts include economical mate, model mate, and ideal mate. An economical mate is a position such that all of the attacker's pieces contribute to the checkmate, with the (optional) exception of the king and the pawns. The model mate and the ideal mate are both stronger forms of pure mate. When a checkmate is both "pure and economical", it is said to be a model mate. When, in a pure mate, all material on the board of either color plays a direct role in the checkmate, it is said to be an ideal mate.