RJ you are the guy with the 2200 grade ( 😕 ) I am only an 1800 player.
For someone who solves SG's difficult set mates without any hassle usually the
first to post a solution I was surprised you were not first in with the solution.
Then I read Exuma's 2nd post.
"Hahahaha. OK this is impossible."
So it would appear it is not a sound mate in 6 and that is why your computer
has failed to find it and you are posting variations all over the place like
a frustrated fish.
Fritz has failed to find it, your next usual step when trolling a post is to cut and
paste something from WIKI but that is no help here, so you do the next bext thing
and wake me up.
So now I have been dragged into this position I suppose I had better
try and sort it out. (me being the RHP Guru and all.) 😉
In the original post we see Exuma has also posted:
"Hint - you must sac the rook. "
Must I? I don't like the word 'must' in problems.
I'm now thinking for there to be a mate in 6 White MUST take the Rook
even if it is not the best move.
So Black is going to make a move and White no matter what Black plays
will take the d3 Rook.
I saw Nc6 punted so 1...Nc6. 2.Kxd3
Tom Tom said this does work because the King can get away to c2.
But 2...Nxb4+
The square c2 is covered.
3.Ke2 Qh5+ 4.Ke1 Nd3 mate.
But that is not mate in 6 I hear you howl.
Yes it is.
You have to try and interpretate what Exuma perhaps means.
The key move is 1....Nc6
Then
after that counting both moves it is a mate in 6.
2. Kxd3 Nxb4+ 3. Ke2 Qh5+ 4. Ke1 Nd3 mate.
That is 3 moves for White and three moves for Black (3 + 3 = 6)
Of course it is not correct in pure problem terminology, it should be
Black to play and mate in four, the King must take on d3.
But Exuma is a good lad, I won't hold that against him.
Greenpawn has spoken. Let it be so. 🙂