Let C be a proper, closed subset with nonempty interior in a normed space X. We define four variants of modulus of convexity for C and prove that they all coincide. This result, which is classical and wellknown for C = B_X (the unit ball of X), requires a less easy proof than the particular case of B_X. We also show that if the modulus of convexity of C is not identically null, then C is bounded. This extends a result by M.V. Balashov and D. Repovs.

Moduli of uniform convexity for convex sets / C.A. De Bernardi, L. Vesely. - In: ARCHIV DER MATHEMATIK. - ISSN 0003-889X. - (2024), pp. 1-10. [Epub ahead of print] [10.1007/s00013-024-02031-8]

Moduli of uniform convexity for convex sets

C.A. De Bernardi
Primo
;
L. Vesely
Ultimo
2024

Abstract

Let C be a proper, closed subset with nonempty interior in a normed space X. We define four variants of modulus of convexity for C and prove that they all coincide. This result, which is classical and wellknown for C = B_X (the unit ball of X), requires a less easy proof than the particular case of B_X. We also show that if the modulus of convexity of C is not identically null, then C is bounded. This extends a result by M.V. Balashov and D. Repovs.
Normed linear space; Convex body; Uniformly convex set; Modulus of convexity;
Settore MATH-03/A - Analisi matematica
   Piano di Sostegno alla Ricerca 2015-2017 - Linea 2 "Dotazione annuale per attività istituzionali" (anno 2021)
   UNIVERSITA' DEGLI STUDI DI MILANO
2024
20-lug-2024
https://link.springer.com/article/10.1007/s00013-024-02031-8
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/1106931
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