CONJUGACY AND RIGIDITY FOR NONPOSITIVELY CURVED MANIFOLDS OF HIGHER RANK

Let M and N be compact Riemannian manifolds with sectional curvature K less than or equal to 0 such that M has dimension greater than or equ al to 3 and rank greater than or equal to 2. If there exists a C-0 con jugacy F between the geodesic flows of the unit tangent bundles of M a nd N, then there exists an isometry G:M --> N that induces the same is omorphism as F between the fundamental groups of M and N.