论文标题

矢量值多项式,指数多项式和矢量值谐波分析

Vector valued polynomials, exponential polynomials and vector valued harmonic analysis

论文作者

Laczkovich, Miklos

论文摘要

让$ g $是带有单位的拓扑亚伯式半群,让$ e $为banach空间,让$ c(g,e)$表示连续功能$ f \ colon g \ to e $。如果有$ n \ ge 0 $,则c(g,e)$中的函数$ f \是一个通用的多项式,如果每个$ n \ ge ge 0 $,以至于每个$δ_{h_1} \ldotsΔ_{h_ {h_ {n+1}} f = 0 $对于每个$ h_1,h_1,\ ldots,h_ ldots,h_ fldots,h_ fldots,h_ {n+1} $ restor。我们说,如果是多项式,则c(g,e)$中的$ f \是多项式,其翻译的线性跨度为有限的尺寸; $ f $是一个w-u \ circ f $,对于每个$ u \ e^*$中的每个$ u \,而$ f $是本地多项式,如果它是每个有限生成的subsemigroup,则是本地多项式。我们表明,每个类别的多项式,W-多项式,广义多项式,局部多项式都包含在下一类中。如果$ g $是一个阿贝尔集团,并且具有一个密集的亚组,则具有有限的扭转等级,那么这些班级是一致的。我们还介绍了指数多项式的类别和W-Expo \ - 性多项式,并与多项式和W-PolyNomials建立其表示并建立联系。我们还研究了$ c(g,e)$类中的光谱合成和分析。众所周知,如果$ g $是一个紧凑的阿贝利安集团,而$ e $是一个巴拉克空间,那么频谱合成在$ c(g,e)$中。另一方面,我们表明,如果$ g $是一个无限且离散的阿贝尔集团,而$ e $是无限尺寸的Banach空间,那么即使是光谱分析在$ c(g,e)$中也会失败。但是,如果$ g $是离散的,则具有有限的扭转等级,并且如果$ e $是有限尺寸的Banach空间,那么Spectral Synthesis在$ C(g,e)$中成立。

Let $G$ be a topological Abelian semigroup with unit, let $E$ be a Banach space, and let $C(G,E)$ denote the set of continuous functions $f\colon G\to E$. A function $f\in C(G,E)$ is a generalized polynomial, if there is an $n\ge 0$ such that $Δ_{h_1} \ldots Δ_{h_{n+1}} f=0$ for every $h_1 ,\ldots , h_{n+1} \in G$, where $Δ_h$ is the difference operator. We say that $f\in C(G,E)$ is a polynomial, if it is a generalized polynomial, and the linear span of its translates is of finite dimension; $f$ is a w-polynomial, if $u\circ f$ is a polynomial for every $u\in E^*$, and $f$ is a local polynomial, if it is a polynomial on every finitely generated subsemigroup. We show that each of the classes of polynomials, w-polynomials, generalized polynomials, local polynomials is contained in the next class. If $G$ is an Abelian group and has a dense subgroup with finite torsion free rank, then these classes coincide. We introduce the classes of exponential polynomials and w-expo\-nential polynomials as well, establish their representations and connection with polynomials and w-polynomials. We also investigate spectral synthesis and analysis in the class $C(G,E)$. It is known that if $G$ is a compact Abelian group and $E$ is a Banach space, then spectral synthesis holds in $C(G,E)$. On the other hand, we show that if $G$ is an infinite and discrete Abelian group and $E$ is a Banach space of infinite dimension, then even spectral analysis fails in $C(G,E)$. If, however, $G$ is discrete, has finite torsion free rank and if $E$ is a Banach space of finite dimension, then spectral synthesis holds in $C(G,E)$.

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