Y. Rakotondratsimba

Abstract
For a given weight $u(.)$ another weight $v(.)=(\Cal R u)(.)$ is found such that the fractional integral operator $I_\alpha$, $0<\alpha<n$, is bounded from the weighted Lebesgue space $L^p(\Bbb R^n,v(x)dx)$ into $L^p(\Bbb R^n,u(x)dx)$ whenever $1<p< n/\alpha$.