What is the B+N checkmate position that leads to a longest mate? Black is trying to avoid a mating net that forces it into the wrong corner. To build the mating net, the White king should cut the black king off the center first, by controlling the center itself. Black can resist that without getting into a form of a mating net. I thought it might be this position where black has no danger of a mating net and has cut the white king off the center.
[FEN &quot;6BK/5N2/5k2/8/8/8/8/8 w - - 0 1&quot;]

I want to capture the essence of this checkmate without relying on brute force search. Just defining general goals that can be extracted from any position.
I am not asking the technique of mating, just how to express them clearly in a systematic way to a computer.
Using the syzygy tablebases by just putting some B+N position in, and looking for the note that says what the longest one is, we can find that it's
8/8/8/6B1/8/8/4k3/1K5N b - - 0 1

with a DTM (depth to mate, in plies/half moves) of 65.
This is probably due to the discoordination of all of white's pieces