%0 Journal Article %A Clark, Lisa Orloff %A Exel, Ruy %A Pardo Espino, Enrique %A Sims, Aidan %A Starling, Charles %T Simplicity of algebras associated to non-hausdorff groupoids %D 2018 %U http://hdl.handle.net/10498/20604 %X We prove a uniqueness theorem and give a characterization of simplicity for Steinberg algebras associated to non-Hausdorff ample groupoids. We also prove a uniqueness theorem and give a characterization of simplicity for the C*-algebra associated to non-Hausdorff ́etale groupoids. Then we show how our results apply in the setting of tight representations of inverse semigroups, groups acting on graphs, and self-similar actions. In particular, we show that C*-algebra and the complex Steinberg algebra of the self-similar action of the Grigorchuk group are simple but the Steinberg algebra with coefficients in Z_2 is not simple. %K Groupoid C*-algebra %K Steinberg algebra %K Self-similar graph algebra %~ Universidad de Cádiz