“Letztform” is the term given to the perfect rendering of an idea. It
would be difficult to improve on this gem.
1.Sb2 Kb4 2.Sc4+ Kc3 3.Se3+ Kd2 4.Sd1+ Ke1 5.Sg4 Bxc6
The knight performs a rundlauf, helping the white king to cross the board by interfering with another piece each time. As solvers noted, the problem is easily solved because realistically there is only one possible mating position.
Richard Stein: The knight embarks on a rundlauf, screening a white king beeline every step of the way. The mate is a model. Perfect rendering of an idea, indeed. Finally one has to wonder: Honourable Mention? Is that all? (The idea had been shown before, so the award was for the perfect construction. Usually a degree of originality will be necessary to gain a prize – MM)
Ravi Shankar: The type of problem which you will solve immediately or take a long time to solve. But you will enjoy it better if you take long! A real gem!