Paper detail

Persistence of normally hyperbolic invariant manifolds in the absence of rate conditions

We consider perturbations of normally hyperbolic invariant manifolds, under which they can lose their hyperbolic properties. We show that if the perturbed map which drives the dynamical system exhibits some topological properties, then the manifold is perturbed to an invariant set. The main feature is that our results do not require the rate conditions to hold after the perturbation. In this case the manifold can be perturbed to an invariant set, which is not a topological manifold. Our method is not perturbative. It can be applied to establish invariant sets within a prescribed neighbourhood also in the absence of a normally hyperbolic invariant manifold prior to perturbation. The work is in the setting of nonorientable Banach vector bundles, without needing to assume invertibility of the map.