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Cauchy problem for semilinear wave equation with time-dependent metrics (1102.4174v1)
Published 21 Feb 2011 in math.AP
Abstract: We establish the existence of weak solutions $u$ of the semilinear wave equation $\partial_t2 u-\textrm{div}_x(a(t,x)\nabla_xu)=f_k(u)$ where $a(t,x)$ is equal to $1$ outside a compact set with respect to $x$ and a non-linear term $f_k$ which satisfies $\vert f_k(u)\vert\leq C\vert u\vertk$. For some non-trapping time-periodic perturbations $a(t,x)$, we obtain the long time existence of solution for small initial data.