Resumen de Lorentzian Kleinian groups
Charles Frances
In this article we introduce some basic tools for the study of Lorentzian Kleinian groups. These groups are discrete subgroups of the Lorentzian M\"obius group $O(2,n)$, acting properly discontinuously on some nonempty open subset of Einstein's universe, the Lorentzian analogue of the conformal sphere.
