Let A be an open convex subset of a real normed linear space X. We prove that if the boundary of A contains a non-LUR point then there exists a Lipschitz quasiconvex function f from A to R not admitting any continuous quasiconvex extension to the whole X.

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Carlo Alberto De Bernardi

Dip. di Matematica per le Scienze Economiche, Finanziarie ed Attuariali, Università Cattolica del Sacro Cuore, Milano, Italy

carloalberto.debernardi@unicatt.it

Libor Vesely

Dip. di Matematica "F. Enriques", Università degli Studi di Milano, Italy

libor.vesely@unimi.it

C. A. De Bernardi, L. Vesely. “Rotundity Properties, and Non-Extendability of Lipschitz Quasiconvex Functions.” Journal of Convex Analysis 30 (2023), No. 1, 329–342.