In this survey paper, we shall derive the following result. Theorem A. Let M denote a closed Riemannian manifold with nonpositive sectional curvature and let M̃ be the universal cover of M with the lifted metric. Suppose that the universal cover M̃ contains no totally geodesic embedded Euclidean plane R (i.e., M is a visibility manifold ). Then Gromov’s simplicial volume ‖M‖ is non-zero. Conseque...
