Abstract
A complete characterization of the extremal subsets of Hilbert spaces, which is an infinite-dimensional generalization of the classical Jung theorem, is given. The behavior of the set of points near the Chebyshev sphere of such a subset with respect to the Kuratowski and Hausdorff measures of noncompactness is investigated.
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Bibliography
W. L. Bynum, “Normal structure coe.cients for Banach spaces,” Pacific J. Math., 86 (1980), 427–436.
A. L. Garkavi, “On Chebyshev centers and convex hulls of set,” Uspekhi Mat. Nauk [Russian Math. Surveys], 19 (1964), no. 6, 139–145.
H. W. E. Jung, “Über die kleinste Kugel, die eine räumliche Figur einschliesst, ” J. Reine Angew. Math., 123 (1901), 241–257.
L. Danzer, B. Grunbaum, and V. Klee, Helly’s Theorem and Its Relatives, Amer. Math. Soc., Providence, R. I., 1963; Russian transl.: Mir, Moscow, 1968.
N. A. Routledge, “A result in Hilbert space,” Quart. J. Math., 3 (1952), no. 9, 12–18.
V. I. Berdyshev, “A relationship between the Jackson inequality and a geometric problem,” Mat. Zametki [Math. Notes], 3 (1968), no. 3, 327–338.
J. Daneš, “On the radius of a set in a Hilbert space,” Comment. Math. Univ. Carolin., 25 (1984), no. 2, 355–362.
N. M. Gulevich, “The radius of a compact set in a Hilbert space,” Zap. Nauchn. Sem. LOMI [J. Soviet Math.], 164 (1988), 157–158.
J. R. L. Webb and W. Zhao, “On connections between set and ball measures of non-compactness,” Bull. London Math. Soc., 22 (1990), 471–477.
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Translated from Matematicheskie Zametki, vol. 80, no. 2, 2006, pp. 231–239.
Original Russian Text Copyright © 2006 by V. Nguen-Khac, K. Nguen-Van.
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Nguen-Khac, V., Nguen-Van, K. An infinite-dimensional generalization of the Jung theorem. Math Notes 80, 224–232 (2006). https://doi.org/10.1007/s11006-006-0131-6
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DOI: https://doi.org/10.1007/s11006-006-0131-6