Acta mathematica scientia,Series B ›› 2018, Vol. 38 ›› Issue (2): 643-650.doi: 10.1016/S0252-9602(18)30771-9

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A NOTE IN APPROXIMATIVE COMPACTNESS AND MIDPOINT LOCALLY K-UNIFORM ROTUNDITY IN BANACH SPACES

Chunyan LIU, Zihou ZHANG, Yu ZHOU   

  1. School of Mathematics Physics and Statistics, Shanghai University of Engineering Science, Shanghai 201620, China
  • Received:2016-10-28 Online:2018-04-25 Published:2018-04-25
  • Contact: Zihou ZHANG E-mail:zhz@sues.edu.cn
  • Supported by:

    Zihou Zhang is supported by the National Natural Science Foundation of China (11671252); Yu Zhou is supported by the National Natural Science Foundation of China (11771278).

Abstract:

In this article, we prove the following results:(1) A Banach space X is weak midpoint locally k-uniformly rotund if and only if every closed ball of X is an approximatively weakly compact k-Chebyshev set; (2) A Banach space X is midpoint locally k-uniformly rotund if and only if every closed ball of X is an approximatively compact k-Chebyshev set.

Key words: k-Chebyshev set, approximatively weak compactness, approximative compactness, weak midpoint locally k-uniform rotundity, midpoint locally k-uniform rotundity, k-strict rotundity

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