Since... 1994!

Pauli's Quadruplets

(White: Ka7, Qg4, Rh6, b4. Black: Kb5.)

White to move and mate in 3


Mate in 3 moves,

(a) in the position shown in the diagram.

(b) with the white king in a8 instead of a7.

(c) with the white king in e7 instead of a7.

(d) with all pieces moved one row down.