Schauder-Orlicz decompositions, $\ell_Φ$-decompositions and pseudo-Daugavet property

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1. Verfasser: Marchenko, Vitalii
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Veröffentlicht: 2024
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author Marchenko, Vitalii
author_facet Marchenko, Vitalii
contents The concept of $\ell_Φ$-decomposition, extending the concept of $\ell_{p}$-decomposition of a Banach space, is presented and basic properties of Schauder-Orlicz decompositions and $\ell_Φ$-decompositions are studied. We show that Schauder-Orlicz decompositions are orthogonal in a sense of Grinblyum-James and Singer. Simple constructions of $\ell_{p}$-decompositions and Schauder-Orlicz decompositions in $L_p$ are presented. We prove that in the class of spaces possessing pseudo-Daugavet property, which includes classical $L_p$, $1\leq p\neq 2$, and $C$, Schauder-Orlicz decompositions with at least one finite dimensional subspace do not exist. It follows that Kato theorem on similarity for sequences of projections [1] cannot be extended to spaces from this class. Moreover we show that Banach spaces, possessing Schauder-Orlicz decompositions with at least one finite dimensional subspace, do not have pseudo-Daugavet property. Thus for Banach spaces $X$ possessing Schauder-Orlicz decompositions we obtain the following characterization of pseudo-Daugavet property: $X$ has pseudo-Daugavet property if and only if there is no Schauder-Orlicz decomposition in $X$ with at least one finite dimensional subspace if and only if there is no Schauder-Orlicz decomposition in $X$, which is an FDD.
format Preprint
id arxiv_https___arxiv_org_abs_2402_09350
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Schauder-Orlicz decompositions, $\ell_Φ$-decompositions and pseudo-Daugavet property
Marchenko, Vitalii
Functional Analysis
46B15, 46E30, 46B20, 46B50, 46B04, 46B45, 41A65
The concept of $\ell_Φ$-decomposition, extending the concept of $\ell_{p}$-decomposition of a Banach space, is presented and basic properties of Schauder-Orlicz decompositions and $\ell_Φ$-decompositions are studied. We show that Schauder-Orlicz decompositions are orthogonal in a sense of Grinblyum-James and Singer. Simple constructions of $\ell_{p}$-decompositions and Schauder-Orlicz decompositions in $L_p$ are presented. We prove that in the class of spaces possessing pseudo-Daugavet property, which includes classical $L_p$, $1\leq p\neq 2$, and $C$, Schauder-Orlicz decompositions with at least one finite dimensional subspace do not exist. It follows that Kato theorem on similarity for sequences of projections [1] cannot be extended to spaces from this class. Moreover we show that Banach spaces, possessing Schauder-Orlicz decompositions with at least one finite dimensional subspace, do not have pseudo-Daugavet property. Thus for Banach spaces $X$ possessing Schauder-Orlicz decompositions we obtain the following characterization of pseudo-Daugavet property: $X$ has pseudo-Daugavet property if and only if there is no Schauder-Orlicz decomposition in $X$ with at least one finite dimensional subspace if and only if there is no Schauder-Orlicz decomposition in $X$, which is an FDD.
title Schauder-Orlicz decompositions, $\ell_Φ$-decompositions and pseudo-Daugavet property
topic Functional Analysis
46B15, 46E30, 46B20, 46B50, 46B04, 46B45, 41A65
url https://arxiv.org/abs/2402.09350