Is there a Connection between Local and Global (In-)Stability?

Abstract

We review two criteria which have been used to predict the onset of large scale stochasticity in Hamiltonian systems. We show that one of them, due to Toda and based on a local stability analysis of the equations of motion, is inconclusive. An approach based on the local Riemannian curvature K of trajectories correctly predicts chaos if K < 0 everywhere, but·no further conclusions can be drawn. New (counter-)examples are provided.