METRIC PROJECTIONS AFTER RENORMING

被引：8

作者：

VESELY, L

机构：

[1] Faculty of Mathematics and Physics, KMA, 18600 Praha 8

来源：

JOURNAL OF APPROXIMATION THEORY | 1991年 / 66卷 / 01期

关键词：

D O I：

10.1016/0021-9045(91)90057-H

中图分类号：

O1 [数学];

学科分类号：

0701 ; 070101 ;

摘要：

A multi-valued mapping of a reflexive real Banach space into its subspace is a metric projection for a suitable equivalent norm iff it has non-empty closed convex values, is norm-to-weak upper semi-continuous, and is semi-linear. As an application of this characterization we prove that, given an infinite-dimensional subspace of codimension at least two in a reflexive space, there exists an equivalent norm such that the subspace is Chebyshev but the metric projection is not continuous. © 1991.

引用

页码：72 / 82

页数：11