English

Two characterizations of the standard unit vector basis of $l_1$

Functional Analysis 2007-05-23 v1

Abstract

We show that for a sequence in a Banach space, the property of being stable under large perturbations characterizes the property of being equivalent to the unit vector basis of l1l_1. We show that a normalized unconditional basic sequence in l1l_1 that is semi-normalized in ll_\infty is equivalent to the standard unit vector basis of~l1l_1.

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Cite

@article{arxiv.math/0010128,
  title  = {Two characterizations of the standard unit vector basis of $l_1$},
  author = {David Mitra},
  journal= {arXiv preprint arXiv:math/0010128},
  year   = {2007}
}

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Latex. 8 pgs