Rigidity of Hilbert metrics

We study the groups of isometries for Hilbert metrics on bounded open convex domains in R-n and show that if C is such a set with a strictly convex boundary, the Hilbert geometry is asymptotically Riemannian at infinity. As a consequence of this result, we prove there are no Hausdorff quotients of C by isometry subgroups with finite volume except when partial derivativeC is an ellipsoid.