A law of large numbers concerning the distribution of critical points of random Fourier series

Fuente: arXiv
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Main Authors: Fu, Qiangang "Brandon'', Nicolaescu, Liviu I.
Format: Preprint
Published: 2024
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author Fu, Qiangang "Brandon''
Nicolaescu, Liviu I.
author_facet Fu, Qiangang "Brandon''
Nicolaescu, Liviu I.
contents On the flat torus $\mathbb{T}^m=\mathbb{R}^m/\mathbb{Z}^m$ with angular coordinates $\vecθ$ we consider the random function $F_R=\mathfrak{a}\big(\, R^{-1} \sqrtΔ\,\big) W$, where $R>0$, $Δ$ is the Laplacian on this flat torus, $\mathfrak{a}$ is an even Schwartz function on $\mathbb{R}$ such that $\mathfrak{a}(0)>0$ and $W$ is the Gaussian white noise on $\mathbb{T}^m$ viewed as a random generalized function. For any $f\in C(\mathbb{T}^m)$ we set \[ Z_R(f):=\sum_{\nabla F_R(\vecθ)=0} f(\vecθ) \] We prove that if the support of $f$ is contained in a geodesic ball of $\mathbb{T}^m$, then the variance of $Z_R(f)$ is asymptotic to $const\times R^{m}$ as $R\to\infty$. We use this to prove that if $m\geq 2$, then as $N\to\infty$ the random measures $N^{-m}Z_N(-)$ converge a.s. to an explicit multiple of the volume measure on the flat torus.
format Preprint
id arxiv_https___arxiv_org_abs_2412_07690
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A law of large numbers concerning the distribution of critical points of random Fourier series
Fu, Qiangang "Brandon''
Nicolaescu, Liviu I.
Probability
60D05, 60F15, 60F17,
On the flat torus $\mathbb{T}^m=\mathbb{R}^m/\mathbb{Z}^m$ with angular coordinates $\vecθ$ we consider the random function $F_R=\mathfrak{a}\big(\, R^{-1} \sqrtΔ\,\big) W$, where $R>0$, $Δ$ is the Laplacian on this flat torus, $\mathfrak{a}$ is an even Schwartz function on $\mathbb{R}$ such that $\mathfrak{a}(0)>0$ and $W$ is the Gaussian white noise on $\mathbb{T}^m$ viewed as a random generalized function. For any $f\in C(\mathbb{T}^m)$ we set \[ Z_R(f):=\sum_{\nabla F_R(\vecθ)=0} f(\vecθ) \] We prove that if the support of $f$ is contained in a geodesic ball of $\mathbb{T}^m$, then the variance of $Z_R(f)$ is asymptotic to $const\times R^{m}$ as $R\to\infty$. We use this to prove that if $m\geq 2$, then as $N\to\infty$ the random measures $N^{-m}Z_N(-)$ converge a.s. to an explicit multiple of the volume measure on the flat torus.
title A law of large numbers concerning the distribution of critical points of random Fourier series
topic Probability
60D05, 60F15, 60F17,
url https://arxiv.org/abs/2412.07690