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Journal of Convex Analysis 29 (2022), No. 2, 411--442 Copyright Heldermann Verlag 2022 On the Convexity of Level-Sets of Probability Functions Yassine Laguel Université Grenoble Alpes, CNRS, Grenoble INP, LJK, France laguel.yassine@gmail.com Wim Van Ackooij EDF R&D OSIRIS, Palaiseau, France wim.van-ackooij@edf.fr Jérôme Malick Université Grenoble Alpes, CNRS, Grenoble INP, LJK, France jerome.malick@univ-grenoble-alpes.fr Guilherme Matiussi Ramalho Federal University of Santa Catarina, LABPLAN, Santa Catarina, Brazil matiussipoli@gmail.com In decision-making problems under uncertainty, probabilistic constraints are a valuable tool to express safety of decisions. They result from taking the probability measure of a given set of random inequalities depending on the decision vector. Even if the original set of inequalities is convex, this favourable property is not immediately transferred to the probabilistically constrained feasible set and may in particular depend on the chosen safety level. In this paper, we provide results guaranteeing the convexity of feasible sets to probabilistic constraints when the safety level is greater than a computable threshold. Our results extend all the existing ones and also cover the case where decision vectors belong to Banach spaces. The key idea in our approach is to reveal the level of underlying convexity in the nominal problem data (e.g., concavity of the probability function) by auxiliary transforming functions. We provide several examples illustrating our theoretical developments. Keywords: Probability constraints, convex analysis, elliptical distributions, stochastic optimization. MSC: 90C15, 90C25. [ Fulltext-pdf (347 KB)] for subscribers only. |