Semi etale groupoids and applications

We introduce a class of locally compact Hausdorff groupoids and show how to associate C*-algebras to them in a way which generalizes the reduced C*-algebra of an 'etale groupoid. Focusing on criteria for simplicity and existence of Cartan subalgebras, we obtain results which both generalize and improve on the corresponding results from the 'etale case. In the second part we apply the results to dynamical systems and subshifts.