D-branes on Singularities: New Quivers from Old

In this paper we present simplifying techniques which 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 $N\to G\to G\mathrm{/}N$. As such, the orbifold $M\mathrm{/}G$ is easier to compute as $(M\mathrm{/}N)\mathrm{/}(G\mathrm{/}N)$ and we present graphical rules which allow fast computation given the $M\mathrm{/}N$ quiver.