D-branes on singularities: New quivers from old

In this paper we present simplifying techniques that allow one to compute the quiver diagrams for various D-branes at (non-Abelian) orbifold singularities with and without discrete torsion. The main idea behind the construction is to take the orbifold of an orbifold. Many interesting discrete groups fit into an exact sequence $\overrightarrow{N}\overrightarrow{G}G/N.\mathrm{}$ As such, the orbifold $\mathcal{M}/G$ is easier to compute as $(\mathcal{M}/N)/(G/N)\mathrm{}$ and we present graphical rules that allow fast computation given the $\mathcal{M}/N$ quiver.