Orthogonal bases of exponential functions for infinite convolutions

Fuente: arXiv
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Main Authors: Miao, Jun Jie, Zhao, Hong Bo
Format: Preprint
Published: 2024
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_version_ 1866917688462278656
author Miao, Jun Jie
Zhao, Hong Bo
author_facet Miao, Jun Jie
Zhao, Hong Bo
contents Let $μ$ denot the infinite convolution generated by $\{(N_k,B_k)\}_{k=1}^\infty$ given by $$ μ=δ_{{N_1}^{-1}B_1}\astδ_{(N_1N_2)^{-1}B_2}\ast\dots\astδ_{(N_1N_2\cdots N_k)^{-1}B_k} *\cdots. $$ where $B_k$ is a complete residue system for each integer $k>0$. We write $$ ν_{>k}=δ_{N_{k+1}^{-1} B_{k+1}} * δ_{(N_{k+1} N_{k+2})^{-1} B_{k+2}} * \cdots. $$ Since the elements in $B_k$ may have very large absolute values, the infinite convolution may not be compactly supported. In this paper, we study the necessary and sufficient conditions for such infinite convolutions being a spectral measure. Generally, for such infinite convolutions, the necessary conditions for spectrality mainly depend on the properties of the polynomials generated by the complete residue systems. The main result shows that if every $B_k$ satisfies uniform discrete zero condition, and $\{ν_{>k}\}_{k=1}^\infty$ is {\it tight}, then $\# B_k | N_k$ for all integers $k\geq 2$. For some special complete residue systems $\{B_k\}_{k=1}^\infty$, we provide the necessary and sufficient conditions for $μ$ being a spectral measure.
format Preprint
id arxiv_https___arxiv_org_abs_2406_05373
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Orthogonal bases of exponential functions for infinite convolutions
Miao, Jun Jie
Zhao, Hong Bo
Functional Analysis
42A85, 42C05
Let $μ$ denot the infinite convolution generated by $\{(N_k,B_k)\}_{k=1}^\infty$ given by $$ μ=δ_{{N_1}^{-1}B_1}\astδ_{(N_1N_2)^{-1}B_2}\ast\dots\astδ_{(N_1N_2\cdots N_k)^{-1}B_k} *\cdots. $$ where $B_k$ is a complete residue system for each integer $k>0$. We write $$ ν_{>k}=δ_{N_{k+1}^{-1} B_{k+1}} * δ_{(N_{k+1} N_{k+2})^{-1} B_{k+2}} * \cdots. $$ Since the elements in $B_k$ may have very large absolute values, the infinite convolution may not be compactly supported. In this paper, we study the necessary and sufficient conditions for such infinite convolutions being a spectral measure. Generally, for such infinite convolutions, the necessary conditions for spectrality mainly depend on the properties of the polynomials generated by the complete residue systems. The main result shows that if every $B_k$ satisfies uniform discrete zero condition, and $\{ν_{>k}\}_{k=1}^\infty$ is {\it tight}, then $\# B_k | N_k$ for all integers $k\geq 2$. For some special complete residue systems $\{B_k\}_{k=1}^\infty$, we provide the necessary and sufficient conditions for $μ$ being a spectral measure.
title Orthogonal bases of exponential functions for infinite convolutions
topic Functional Analysis
42A85, 42C05
url https://arxiv.org/abs/2406.05373