Abstract
For an infinite-dimensional Banach space X, we demonstrate the equivalence of the following two properties. One, the space is B-convex, that is, it possesses a nontrivial type. Two, X possesses the convexification property, that is, the Hausdorff distance between the Minkowski average of k subsets of the unit ball, and the convex hull of the average, converges to 0 as k tends to infinity. A rate for the convergence is provided. The result is used to establish a general Strong Law of Large Numbers for random bounded subsets of the Banach space.
References
- K. J. Arrow, F. H. Hahn: General Competitive Analysis, Holden-Day, San Francisco (1971).Google Scholar
- Z. Artstein: Convexification estimates for Minkowski averages in infinite dimensions, Pure Appl. Funct. Anal. 6/4 (2021) 709–718.Google Scholar
- Z. Artstein, J. C. Hansen: Convexification in limit laws of random sets in Banach spaces, Ann. Probability 13 (1985) 307–309.https://doi.org/10.1214/aop/1176993083Google Scholar
- Z. Artstein, R. A. Vitale: A strong law of large numbers for random compact sets, Ann. Probability 3 (1975) 879–882.https://doi.org/10.1214/aop/1176996275Google Scholar
- A. Beck: A Convexity condition in Banach spaces and the strong law of large numbers, Proc. Amer. Math. Soc. 13 (1962) 329–334.https://doi.org/10.1090/S0002-9939-1962-0133857-9Google Scholar
- A. Beck, D. P. Giesy, P. Warren: Recent developments in the theory of strong laws of large numbers for vector-valued ranom variables, Theory Probability Appl. 20 (1975) 127–134.https://doi.org/10.1137/1120010Google Scholar
- M. Fradelizi, M. Madiman, A. Marsiglietti, A. Zvavitch: The convexification effect of Minkowski summation, EMS Surveys Math. Sci. 5 (2018) 1–164.https://doi.org/10.4171/emss/26Google Scholar
- C. Hess: Set-valued integration and set-valued probability theory: an overview, in: Handbook of Measure Theory Vol I, Chapter 14, E. Pap (ed.), North-Holland, Amsterdam (2002) 617–673.https://doi.org/10.1016/B978-044450263-6/50015-4Google Scholar
- V. Kadets: The domain of weak limits of integral Riemann sums of an abstract function, Soviet Math. 32/9 (1988) 56–66; transl. from the Russian, Izv. Vyssh. Uchebn. Zaved., Mat. 316/9 (1988) 39–46.Google Scholar
- M. Kadets, V. Kadets: Series in Banach Spaces: Conditional and Unconditional Convergence, transl. from the Russian by A. Iacob, Operator Theory: Advances and Applications 94, Birkhäuser, Basel (1997).Google Scholar
- V. Kadets, A. Kulykov, O. Shevchenko: Connection between the Riemann integrability of a multi-valued function and of its convex hull, J. Math. Anal. Appl. 505/2 (2022), art. no. 125652.https://doi.org/10.1016/j.jmaa.2021.125652Google Scholar
- M. Ledoux, M. Talagrand: Probability in Banach spaces. Isoperimetry and Processes, Springer, New York (1991).https://doi.org/10.1007/978-3-642-20212-4Google Scholar
- I. Molchanov: Theory of Random Sets, 2nd ed., Springer, London (2017).https://doi.org/10.1007/978-1-4471-7349-6Google Scholar
- E. Mourier: Elements aléatoires dans un espace de Banach, Ann. Inst. Henri Poincaré 13 (1953) 151–244.Google Scholar
- G. Pisier: Sur les espaces qui ne contiennent pas de ℓ1n uniformément, Séminaire d’Analyse Fonctionnelle 7 (1973-1974) 1–19; http://eudml.org/doc/109118.Google Scholar
- G. Pisier: Geometry of Banach Spaces. Local Finite-Dimensional Theory, Lectures given at the University of Zaragoza, December 1980. compiled by J. Bastero, Universidad de Zaragoza (1983).Google Scholar
- M. L. Puri, D. A. Ralescu: Limit theorems for random compact sets in Banach space, Math. Proc. Cambridge Phil. Soc. 97 (1985) 151–158.https://doi.org/10.1017/S0305004100062691Google Scholar
- R. M. Starr: Quasi-equilibria in markets with non-convex preferences, Econometrica 37 (1969) 25–38.https://doi.org/10.2307/1909201Google Scholar
- P. Wojtaszczyk: Banach Spaces for Analysts, Cambridge University Press, Cambridge (1996).Google Scholar
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