Journal of Convex Analysis 18 (2011), No. 3, 811--821
Copyright Heldermann Verlag 2011
Local U-Convexity
Sudipta Dutta
Department of Mathematics and Statistics, Indian Institute of Technology, Kanpur, India
sudipta@iitk.ac.in
Bor-Luh Lin
Dept. of Mathematics, University of Iowa, Iowa City, U.S.A.
bllin@math.uiowa.edu
K.-S. Lau ["Best approximation by closed sets in Banach spaces", J. Approx. Theory 23 (1978) 29--36] considered the notion of "U-convex spaces" (originally called U-spaces) and showed that both uniform convexity and uniform smoothness imply U-convexity. Also U-convex spaces are uniformly non-square and hence super-reflexive. In this paper we introduce local U-convexity. It is shown that there are two possible localization of U-convexity. We derive our results quantitatively, that is, by the properties of modulus functions. Relationship to modulus of (local) uniform convexity is established and its consequences are discussed.
Keywords: Locally uniformly convex, super-reflexive spaces, U-convexity.
MSC: 46B20
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