We present recent existence results of small amplitude periodic and quasi-periodic solutions of completely resonant nonlinear wave equations. Both infinite-dimensional bifurcation phenomena and small divisors difficulties occur. The proofs rely on bifurcation theory, Nash-Moser implicit function theorems, dynamical systems techniques and variational methods.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-bc77-0-4, author = {Massimiliano Berti}, title = {Nonlinear vibrations of completely resonant wave equations}, journal = {Banach Center Publications}, volume = {75}, year = {2007}, pages = {49-60}, zbl = {1121.35083}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-bc77-0-4} }
Massimiliano Berti. Nonlinear vibrations of completely resonant wave equations. Banach Center Publications, Tome 75 (2007) pp. 49-60. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-bc77-0-4/