This issuePrevious ArticleAsymptotic behavior in time of solutions to the derivative nonlinear Schrödinger equation revisitedNext ArticleConvergence of solitary-wave solutions in a perturbed bi-Hamiltonian dynamical system I. Compactions and peakons
An infinite-dimensional extension of a Poincaré's result concerning the continuation of periodic orbits
We study the existence of periodic
solutions for
the infinite-dimensional second order system $\ddot x=V_{x},\
x\in\mathbb{T}^{\mathbb{Z}_+}.$
Using the Implicit-Function-Theorem, we prove the
existence of time-periodic solutions at "high frequencies"; no "smallness condition" on $V(x)$ is required.