Reflexmate

A reflexmate is easiest to understand through the selfmate: White plays to force an unwilling Black side to checkmate the White king. The reflexmate keeps that goal and adds a compulsory rule: if the side to move can give mate in one, it must do so.

The obligation applies to both White and Black. White must therefore do more than construct a position where Black's mate is unavoidable. White must also avoid gaining an earlier mate against the Black king, because White would be required to play it and would fail the intended goal.

Black resists mating the White king whenever a legal non-compulsory choice remains. Once at least one immediate mating move exists, Black may no longer choose a non-mating move. If several immediate mates are available, Black may choose among them.

The stipulation, the task printed with the diagram, normally states reflexmate in a given number of moves. In a semi-reflexmate, only Black is required to mate whenever possible; White is not subject to that obligation.