Free groups generated by two screw parabolic maps.

In this paper, we provide sufficient conditions for groups generated by two screw parabolic maps of PU (2 , 1) with distinct fixed points to be discrete and free. As an example, we apply our results to the classical group ⟨ g θ , f θ ⟩ constructed in Gusevskii, N., Parker, J.R.: Representations of free Fuchsian groups in complex hyperbolic space. Topology 39, 33–60 (2000). [ABSTRACT FROM AUTHOR]