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 N→G→G/N. As such, the orbifold M/G is easier to compute as (M/N)/(G/N) and we present graphical rules that allow fast computation given the M/N quiver.