In the first part of the paper, Gaussian estimates are used to study L^p-summability of the solution of the wave equation in L^p(Omega) associated with a general operator in divergence form with bounded coefficients. Secondly, we prove that if Omega is a cube in RR^N, then the Laplacian with Dirichlet or Neumann boundary conditions generates an l-times integrated cosine function on L^p(Omega),;1le p 展开▼
