Roland Baier
A pretty logical problem which should not prove too difficult to solve.
With Black poised to queen, short threats are needed, and 1.Rd3? threatening 2.Re3 mate, fails to 1...Bc1.
1.Rd5 threatens 2.Re5, and the only defence is 1...Sd7. 2.Rd6 threatens
3.Re6+ Se5 4.Rxe5, so the knight must return to f8. 3.R1d5 renews the threat at e5, and forces
the knight back to d7. 4.Rd2 removes the possibility of a black bishop guard on e3, setting up two
threats, and Black cannot deal with both. If he plays 4...Sf8 to prevent 5.Re6+, White concludes with
5.R6d3 and 6.Re3 mate.