The Fatou theorem and its converse
The Fatou theorem and its converse
if and only if u(x, y) is in H (see [51). Hence with each function u(x, y) in Hwe can associate a function a(s) and a constant K such that (1.1) and (1.2) hold; we can further assume that a(0) =0. For each u(x, y) in H+, a(s) is nondecreasing …