Uniform hyperbolicity revisited: index of periodic points and equidimensional cycles

摘要

In this paper, we revisit uniformly hyperbolic basic sets and the domination of Oseledets splittings at periodic points. We prove that periodic points with simple Lyapunov spectrum are dense in non-trivial basic pieces of C~r-residual diffeomorphisms on three-dimensional manifolds (r ≥ 1). In the case of the C~1-topology, we can prove that either all periodic points of a hyperbolic basic piece for a diffeomor-phism f have simple spectrum C~1-robustly (in which case f has a finest dominated splitting into one-dimensional sub-bundles and all Lyapunov exponent functions of fare continuous in the weak*-topology) or it can be C~1-approximated by an equidimensional cycle associated to periodic points with robust different signatures. The latter can be used as a mechanism to guarantee the coexistence of infinitely many periodic points with different signatures.