科研之友
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摘要
Let f be a [-10.5pc]C-2 diffeomorphism on a compact manifold. Ledrappier and Young introduced entropies along unstable foliations for an ergodic measure mu. We relate those entropies to covering numbers in order to give a new upper bound on the metric entropy of mu in terms of Lyapunov exponents and topological entropy or volume growth of sub-manifolds. We also discuss extensions to the C1+alpha, alpha > 0, case.
