Hyperspace convergences, bornologies and geometric set functionals
Yogesh Agarwal, Varun Jindal
TL;DR
This paper examines how three unified approaches to hyperspace convergence for a bornology on a metric space relate to one another, focusing on tau_S,d-convergence, bornological convergence S, and gap-excess weak convergence. By leveraging the concept of pointwise Lipschitz enlargements, the authors derive conditions under which tau_S,d agrees with S-convergence and with gap-excess convergence, and they provide new proofs of Attouch-Wets convergence results as corollaries. Key contributions include necessary and sufficient conditions for tau_S,d to coincide with S and to align with LE and GE convergences under stability assumptions, along with a covering criterion that guarantees tau_S,d = tau_GE^S. These results deepen the understanding of the structural and topological relationships among hyperspace convergences and offer practical tools for variational analysis and related optimization contexts.
Abstract
For a bornology $\mathcal{S}$ of subsets of a metric space $(X,d)$, we consider the following unified approaches of hyperspace convergence: convergence induced through uniform convergence of distance functionals ($τ_{\mathcal{S},d}$-convergence); bornological convergence, and the weak convergence induced by a family of gap and excess functionals. An interesting problem regarding these convergences is to investigate when any two of them are equivalent. In this article, we investigate the relation of $τ_{\mathcal{S},d}$-convergence with the other two convergences, which is not completely transparent. As a main tool for our investigation, we use the idea of pointwise enlargement of a set by a positive Lipschitz function. As applications of our results, we provide new proofs of some known results about Attouch-Wets convergence.
