  Buchweitz related the singularity category of a (strongly) Gorenstein ring
and the stable category of maximal Cohen-Macaulay modules by a triangle
equivalence. We phrase his result in a relative categorical setting based on
N-complexes instead of classical 2-complexes. The role of Cohen-Macaulay
modules is played by chains of monics in a Frobenius subcategory of an exact
category. As a byproduct, we provide foundational results on derived categories
of N-complexes over exact categories known from the Abelian case or for
2-complexes.
