Do you know the Babson task?
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If Black promotes to Queen, White must promote to Queen.
If Black promotes to Rook, White must promote to Rook.
If Black promotes to Bishop, White must promote to Bishop.
If Black promotes to Knight, White must promote to Knight.
If Black promotes to Rook, White must promote to Rook.
If Black promotes to Bishop, White must promote to Bishop.
If Black promotes to Knight, White must promote to Knight.
White to play and mate in 4#
If I could take one diagram to a desert island, it would be this one
Leonid Yarosh, when he composed this problem in 1983, was a 26-year old soccer trainer from Kazan, and a complete unknown in the composing world.
Here you can see several Babson tasks:
http://www.jmrw.com/Chess/Yarosh/base.htm