Conférence de systèmes dynamiques.
Résumé
The Mañé-Bochi theorems that the Lyapunov exponents of continuous SL(2)-cocycles over any invertible aperiodic system may always anihilated by arbitrarily small perturbations, unless the cocycle is uniformly hyperbolic. Surprisingly, this is generally false when the base system is not invertible. We present a few examples and discuss how this discovery fits together with other recent progress in this area. This is a joint work with Jiagang Yang (U. F. Fluminense).
