Computer-Generated Chess Problem 01987

This is an original 'KRN vs kpp' mate in 4 chess puzzle or problem (whichever you wish to call it) composed by a computer program, Chesthetica, using the Digital Synaptic Neural Substrate AI computational creativity method. Depending on the type and complexity of the problem desired, a single instance of Chesthetica running on a desktop computer can probably generate anywhere between one and ten problems per hour.

8/8/8/8/8/N1K1ppR1/k7/8 w - - 0 1
White to Play and Mate in 4
Chesthetica v10.63 : Selangor, Malaysia
2018.3.29 1:47:04 AMSolvability Estimate = Moderate
White is over a rook's worth in material but the precise win in this position still needs to be found. Why not time yourself how long it took you to solve this? As a whole, these problems are intended to cater to players of all skill levels.
Solution (Skip to 0:35)