Association Journal of CSIAM
Supervised by Ministry of Education of PRC
Sponsored by Xi'an Jiaotong University
ISSN 1005-3085  CN 61-1269/O1

Chinese Journal of Engineering Mathematics ›› 2017, Vol. 34 ›› Issue (5): 563-570.doi: 10.3969/j.issn.1005-3085.2017.05.010

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Best Simultaneous Approximations in Bochner-Lebesgue Spaces

WEI Hai-hua,   XU Jing-shi   

  1. School of Mathematics and Statistics, Hainan Normal University, Haikou 571158
  • Received:2016-02-01 Accepted:2017-03-06 Online:2017-10-15 Published:2017-12-15
  • Contact: J. Xu. E-mail address: jingshixu@126.com
  • Supported by:
    The National Natural Science Foundation of China (11361020).

Abstract: In this paper, we consider the best simultaneous approximations in Bochner-Lebesgue spaces with respective to Minkowski' norms in Euclidean spaces. Firstly, we give a characterization of best simultaneous approximations by the distance functions. Then, by applying this characterization and a measurable selection theorem we show the simultaneous proximinality of a Bochner-Lebesgue space whose functions take values in a closed separable subspace is equivalent to the simultaneous proximinality of the closed separable subspace. Finally, we conclude that for their equivalence, the separability of the subspace is necessary.

Key words: Bochner-Lebesgue space, simultaneously proximinality, best simultaneous approximation

CLC Number: