“…The latter reaches down to C 1,1 -at least as far as convexity and causality are concerned [16,13,14,5]. However, the Lipschitz property is decisive since it prevents the most dramatic downfalls in causality theory which are known to occur for Hölder continuous metrics [9,3,30,6,17]. More specifically, in the context of the initial value problem for the geodesic equation, the Lipschitz property guarantees the existence of solutions [35] which, due to the special geometry of the models at hand, are even (globally) unique [27].…”