  We present a novel theoretical approach to incorporate electronic
interactions in the study of two-dimensional topological insulators. By
exploiting the correspondence between edge state physics and entanglement
spectrum in gapped topological systems, we deconstruct the system into
one-dimensional channels. This framework enables a simple and elegant inclusion
of fermionic interactions into the discussion of topological insulators. We
apply this approach to the Kane-Mele model with interactions and magnetic
impurities.
