Let ⟨X, d⟩ be a separable metric space. A set-valued function Γ: S ⇉ X defined on a measurable space S whose values are nonempty closed subsets of X is declared measurable provided for each open subset V of X, {s ∈ S: Γ(s) ∩ V ≠ ∅} is a measurable subset of S. In this paper, we look at the relationship between measurability so defined and the Borel measurability of Γ, viewed as a single-valued function into the nonempty closed subsets of X, equipped with either the Hausdorff metric topology or with the Attouch-Wets topology. Our analysis rests on cardinality arguments in conjunction with the representation of these hyperspaces as weak topologies. Applications are given to convex-valued multifunctions.

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Alberto Barbati

Dipartimento di Matematica, Università degli Studi di Milano 20133 Milano, Italy

Gerald Beer

Department of Mathematics, California State University, Los Angeles Los Angeles, CA 90032, USA

Christian Hess

CEREMADE, Université de Paris-Dauphine 75775 Paris 16, France

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A. Barbati, G. Beer, C. Hess. “The Hausdorff Metric Topology, the Attouch-Wets Topology, and the Measurability of Set-Valued Functions.” Journal of Convex Analysis 1 (1994), No. 1, 107–119. https://doi.org/10.68381/jca01008