STRICHARTZ ESTIMATES FOR THE KLEIN–GORDON EQUATION IN ℝ3+1

Abstract

We prove standard and reversed Strichartz estimates for the Klein–Gordon equation in ${ℝ}^{3+1}$. Instead of the Fourier theory, our analysis is based on fundamental solutions of the free equations and fractional integrations. We apply Strichartz estimates to study semilinear Klein–Gordon equations.