This mate-in-three problem by Eric Zepler teaches you everything you need to know about the "Novotny" theme. The basic idea of the Novotny is to jettison a white piece on a square where the actions of two defending pieces cross. Neither piece can capture without interfering with the action of the other. Here, the d6 square is begging for a bit of interference, but 1.d6 (hoping for 1...Bxd6 2.Bc6 mate) is met by 1...Rxd6, and 1.Bd6 (when 1...Rxd6 2.Qb3 is mate) is met by 1...Bxd6!
The solution is beautiful: White starts with 1.Nf7! producing an interference on f7. Now 1...Bxf7 blocks the rook on h7 and leaves Black defenceless after 2.Bd6! while 1...Rxf7 blocks the g8-bishop allowing 2.d6! and mate next move.
Finally, if Black does not capture the knight on f7, he has no defence to the threat of 2.Nd6+ followed by 3.Bc6 mate or 3.Qb3 mate after 2...Bxd6 or 2...Rxd6 respectively. That's four Novotny interferences in total.