Hereditary completeness of Exponential systems $\{e^{λ_n t}\}_{n=1}^{\infty}$ in their closed span in $L^2 (a, b)$ and Spectral Synthesis

Fuente: arXiv
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Autori principali: Zikkos, Elias, Gunatillake, Gajath
Natura: Preprint
Pubblicazione: 2024
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author Zikkos, Elias
Gunatillake, Gajath
author_facet Zikkos, Elias
Gunatillake, Gajath
contents Suppose that $\{λ_n\}_{n=1}^{\infty}$ is a sequence of distinct positive real numbers satisfying the conditions inf$\{λ_{n+1}-λ_n \}>0,$ and $\sum_{n=1}^{\infty}λ_n^{-1}<\infty.$ We prove that the exponential system $\{e^{λ_n t}\}_{n=1}^{\infty}$ is hereditarily complete in the closure of the subspace spanned by $\{e^{λ_n t}\}_{n=1}^{\infty}$ in the space $L^2 (a,b)$. We also give an example of a class of compact non-normal operators defined on this closure which admit spectral synthesis.
format Preprint
id arxiv_https___arxiv_org_abs_2401_01132
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Hereditary completeness of Exponential systems $\{e^{λ_n t}\}_{n=1}^{\infty}$ in their closed span in $L^2 (a, b)$ and Spectral Synthesis
Zikkos, Elias
Gunatillake, Gajath
Functional Analysis
Classical Analysis and ODEs
Complex Variables
30B60, 30B50, 47A10, 46C05
Suppose that $\{λ_n\}_{n=1}^{\infty}$ is a sequence of distinct positive real numbers satisfying the conditions inf$\{λ_{n+1}-λ_n \}>0,$ and $\sum_{n=1}^{\infty}λ_n^{-1}<\infty.$ We prove that the exponential system $\{e^{λ_n t}\}_{n=1}^{\infty}$ is hereditarily complete in the closure of the subspace spanned by $\{e^{λ_n t}\}_{n=1}^{\infty}$ in the space $L^2 (a,b)$. We also give an example of a class of compact non-normal operators defined on this closure which admit spectral synthesis.
title Hereditary completeness of Exponential systems $\{e^{λ_n t}\}_{n=1}^{\infty}$ in their closed span in $L^2 (a, b)$ and Spectral Synthesis
topic Functional Analysis
Classical Analysis and ODEs
Complex Variables
30B60, 30B50, 47A10, 46C05
url https://arxiv.org/abs/2401.01132