In this paper we prove that on every compact C2 hypersurface in R2n bounding a convex set with non-empty interior, either there exists a sequence of variationally visible hyperbolic closed characteristcs with their minimal periods tending to infinity, or there exists at least one variationally visible nonhyperbolic closed characteristic.

In this paper the integer valued ω-index theory parameterized by all ω on the unit circle for paths in the symplectic group Sp(2n) is established. Based on this index theory, the Bott formula of the Malsov-type index theory for iterated paths in Sp(2n) is estalished, the mean index for periodic solutions of Hamiltonian systems is defined, and the increasing estimate of the iterated Maslov-type index in terms of the mean index is proved.

In this paper, suppose L(t,x,p) =12A(x)p·p + V (t, x), A is positive definite and symmetric, and both A and V are C3 and 1-periodic in all of their variables. We prove that the Poincare map (i.e. the time-1-solution map) of the Lagrangian system d dt Lx˙(t, x, x˙)−Lx(t, x, x˙) =0 possesses infinitely many periodic points on Tn produced by contractible integer periodic solutions.

Let