EN
Let $M_{S}$ denote the strong maximal operator. Let $M_{x}$ and $M_{y}$ denote the one-dimensional Hardy-Littlewood maximal operators in the horizontal and vertical directions in ℝ². A function h supported on the unit square Q = [0,1]×[0,1] is exhibited such that $∫_{Q} M_{y}M_{x}h < ∞$ but $∫_{Q} M_{x}M_{y}h = ∞$. It is shown that if f is a function supported on Q such that $∫_{Q} M_{y}M_{x}f < ∞$ but $∫_{Q} M_{x}M_{y}f = ∞$, then there exists a set A of finite measure in ℝ² such that $∫_{A} M_{S}f = ∞$.