A Banach space whose set of norm-attaining functionals is algebraically trivial

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1. Verfasser: Martin, Miguel
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Veröffentlicht: 2024
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author Martin, Miguel
author_facet Martin, Miguel
contents We construct a Banach space $X$ for which the set of norm-attaining functionals $NA(X,\mathbb{R})$ does not contain any non-trivial cone. Even more, given two linearly independent norm-attaining functionals on $X$, no other element of the segment between them attains its norm. Equivalently, the intersection of $NA(X,\mathbb{R})$ with a two-dimensional subspace of $X^*$ is contained in the union of two lines. In terms of proximinality, we show that for every closed subspace $M$ of $X$ of codimension two, at most four elements of the unit sphere of $X/M$ have a representative of norm-one. We further relate this example with an open problem on norm-attaining operators.
format Preprint
id arxiv_https___arxiv_org_abs_2406_07273
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A Banach space whose set of norm-attaining functionals is algebraically trivial
Martin, Miguel
Functional Analysis
Primary 46B04, 46B20, Secondary 41A65, 46B03, 46B22, 46B87
We construct a Banach space $X$ for which the set of norm-attaining functionals $NA(X,\mathbb{R})$ does not contain any non-trivial cone. Even more, given two linearly independent norm-attaining functionals on $X$, no other element of the segment between them attains its norm. Equivalently, the intersection of $NA(X,\mathbb{R})$ with a two-dimensional subspace of $X^*$ is contained in the union of two lines. In terms of proximinality, we show that for every closed subspace $M$ of $X$ of codimension two, at most four elements of the unit sphere of $X/M$ have a representative of norm-one. We further relate this example with an open problem on norm-attaining operators.
title A Banach space whose set of norm-attaining functionals is algebraically trivial
topic Functional Analysis
Primary 46B04, 46B20, Secondary 41A65, 46B03, 46B22, 46B87
url https://arxiv.org/abs/2406.07273