摘要
In this paper,we discuss the relation between τ-strongly Chebyshev,approximatively τ-compact k-Chebyshev,approximatively τ-compact,τ-strongly proximinal and proximinal sets,where τ is the norm or the weak topology.We give some equivalent conditions regarding the above proximinality.Furthermore,we also propose the necessary and sufficient conditions that a half-space is τ-strongly proximinal,approximatively τ-compact and τ-strongly Chebyshev.
作者
张子厚
周宇
刘春燕
周晶
Zihou;ZHANG Yu;ZHOU Chunyan;LIU Jing ZHOU(School of Mathematics Physics and Statistics,Shanghai University of Engineering Science,Shanghai 201620,China)
基金
supported by the National Natural Science Foundation of China(11671252)
supported by the National Natural Science Foundation of China(11771278)。
