Manifolds without focal points are natural generalizations of those of nonpositive curvature. The geodesic flows on rank one manifolds without focal points are classical examples of non-uniformly hyperbolic dynamical systems. The uniqueness of the measure of maximal entropy (MME) for geodesic flows on rank one manifolds of nonpositive curvature was conjectured by A. Katok in 1985 and proved by G. Knieper in 1998. We present how Knieper’s construction of MME via Patterson-Sullivan densities can be extended to the no focal points case. We also discuss the ergodicity of geodesic flows on rank one manifolds without focal points with respect to the Liouville measure.

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