Guido Gentile and Michela Procesi
Conservation of resonant periodic solutions for the 
one-dimensional nonlinear Schroedinger equation
(310K, postscript)

ABSTRACT.  We consider the one-dimensional nonlinear Schr\"odinger equation 
with Dirichlet boundary conditions in the fully 
resonant case (absence of the zero-mass term). 
We investigate conservation of small amplitude periodic-solutions 
for a large set measure of frequencies. In particular we show that 
there are infinitely many periodic solutions which continue 
the linear ones involving an arbitrary number of resonant modes, 
provided the corresponding frequencies are large enough 
and close enough to each other (wave packets with large wave number).