Nuclear Dimension of Subhomogeneous Twisted Groupoid C*-algebras and Dynamic Asymptotic Dimension

We characterize subhomogeneity for twisted étale groupoid C*-algebras and obtain an upper bound on their nuclear dimension. As an application, we remove the principality assumption in recent results on upper bounds on the nuclear dimension of a twisted étale groupoid C*-algebra in terms of the dynamic asymptotic dimension of the groupoid and the covering dimension of its unit space. As a non-principal example, we show that the dynamic asymptotic dimension of any minimal (not necessarily free) action of the infinite dihedral group D∞ on an infinite compact Hausdorff space X is always one. So if we further assume that X is second-countable and has finite covering dimension, then C(X) ᵣ D∞ has finite nuclear dimension and is classifiable by its Elliott invariant.