摘要

We prove an infinite dimensional KAM theorem. As an application, we use the theorem to study the two dimensional nonlinear Schrodinger equation
iu(t) - Delta u + vertical bar u vertical bar(2)u = 0, t is an element of R, x is an element of T(2)
with periodic boundary conditions. We obtain for the equation a Whitney smooth family of small-amplitude quasi-periodic solutions corresponding to finite dimensional invariant tori of an associated infinite dimensional dynamical system.