let $\overset{\backsim} {g}(x)=g(-x)$;
suppose $u,\phi,\psi$ always make the integral significant,$E_n$ is the n-dimensional euclidean space. Then how to prove
$\int_{E_n}(u*\phi)(x)\psi(x)dx=\int_{E_n}u(x)(\overset{\backsim} {\phi}(x)*\psi(x))dx$ ?