Gelfand numbers and widths

被引:13
作者
Edmunds, David E. [2 ]
Lang, Jan [1 ]
机构
[1] Ohio State Univ, Dept Math, Columbus, OH 43210 USA
[2] Univ Sussex, Dept Math, Brighton BN1 9QH, E Sussex, England
关键词
Gelfand numbers; Gelfand widths; s-numbers; Banach spaces; Compact maps;
D O I
10.1016/j.jat.2012.10.008
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
In general, the Gelfand widths (c) over tilde (n)(T) of a map T between Banach spaces X and Y are not equivalent to the Gelfand numbers c(n)(T) of T. We show that (c) over tilde (n)(T) = c(n)(T) (n is an element of N) provided that X and Y are uniformly convex and uniformly smooth, and T has trivial kernel and dense range. (C) 2012 Elsevier Inc. All rights reserved.
引用
收藏
页码:78 / 84
页数:7
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