A king that is attacked three or more times is not considered to be in
check.
Henk Le Grand, the Netherlands
1st Price 151th Thematoernooi
Probleemblad 1993
Bosma Chess. White to mate in two moves.
Solution
1. Rc8! threatens 2. Re8 mate. (Not: 2. f8R, as black can then play Kd8; not 2. f8N, as black can then play Kxd7; not 2. f8B, as black can then play Kd6.)