Boundary theories of static bulk topological phases matter are obstructed in the sense that they cannot be realized on their own as isolated systems. The obstruction can quantified/characterized by quantum anomalies, particular when there is a global symmetry. Similarly, Floquet evolutions realize unitary operators at boundaries. In this paper, we discuss characterization such obstructions usin...

The concept of unitary duality for topological groups was introduced by H. Chu. All mapping spaces are given the compact-open topology. Let G and H be locally compact groups. G" is the space of continuous finite-dimensional unitary representations of G. Let Horn (C, H") denote the space of all continuous maps from G" to H" which preserve degree, direct sum, tensor product and equivalence. We pr...