posted on 2025-05-11, 07:51authored byGerald Beer, Jonathan M. Borwein
In this note we aim to show conclusively that Mosco convergence of convex sets and functions and the associated Mosco topology τ<sub>M</sub> are useful notions only in the reflexive setting. Specifically, we prove that each of the following conditions is necessary and sufficient for a Banach space X to be reflexive: (1) whenever A , A₁, A₂, A₃, ... are nonempty closed convex subsets of X with A = τ<sub>M</sub> — lim A<sub>n</sub> , then A° = τ<sub>M</sub> — lim A°/<sub>n</sub> ; (2) τ<sub>M</sub> is a Hausdorff topology on the nonempty closed convex subsets of X ; (3) the arg min multifunction ∫ ⇉ {x ∈ X : ∫(x) = inf<sub>x</sub> ∫} on the proper lower semicontinuous convex functions on X , equipped with τ<sub>M</sub> , has closed graph.
First published in Proceedings of the American Mathematical Society in Vol. 109, No. 2, pp. 427-436, 1990, published by the American Mathematical Society.