TY - JOUR T1 - Sobolev periodic solutions of nonlinear wave equations in higher spatial dimensions JF - Archive for Rational Mechanics and Analysis Y1 - 2010 A1 - Massimiliano Berti A1 - Philippe Bolle AB - We prove the existence of Cantor families of periodic solutions for nonlinear wave equations in higher spatial dimensions with periodic boundary conditions. We study both forced and autonomous PDEs. In the latter case our theorems generalize previous results of Bourgain to more general nonlinearities of class C k and assuming weaker non-resonance conditions. Our solutions have Sobolev regularity both in time and space. The proofs are based on a differentiable Nash-Moser iteration scheme, where it is sufficient to get estimates of interpolation-type for the inverse linearized operators. Our approach works also in presence of very large "clusters of small divisors". © Springer-Verlag (2009). VL - 195 N1 - cited By (since 1996)6 ER -