Department of Mathematics, University of Zaragoza, 50009-Zaragoza, Spain ; Department of Mathematics, Florida Atlantic University, Boca Raton, Florida 33431 ; Department of Mathematics, University of Zaragoza, 50009-Zaragoza, Spain
Abstract:
For the classical Hardy-Littlewood maximal function , a well known and important estimate due to Herz and Stein gives the equivalence . In the present note, we study the validity of analogous estimates for maximal operators of the form