Maximal functions and the control of weighted inequalities for the fractional integral operator

Abstract

We study weak-type (1, 1) weighted inequalities for the fractional integral operator Iα. We show that the fractional maximal operator Mα controls these inequalities when the weight is radially decreasing. However, we exhibit some counterexamples which show that Mα is not appropriate for this control on general weights. We do provide, nevertheless, some positive results related to this problem by considering other suitable maximal\n\t\t\t\t functions.