Bridging Koopman Operator and time-series auto-correlation based Hilbert-Schmidt operator

Fuente: arXiv
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Autores principales: Zhen, Yicun, Chapron, Bertrand, Mémin, Etienne
Formato: Preprint
Publicado: 2022
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author Zhen, Yicun
Chapron, Bertrand
Mémin, Etienne
author_facet Zhen, Yicun
Chapron, Bertrand
Mémin, Etienne
contents Given a stationary continuous-time process $f(t)$, the Hilbert-Schmidt operator $A_τ$ can be defined for every finite $τ$\cite{Vautard1989SingularSA}. Let $λ_{τ,i}$ be the eigenvalues of $A_τ$ with descending order. In this article, a Hilbert space $\mathcal{H}_f$ and the (time-shift) continuous one-parameter semigroup of isometries $\mathcal{K}^s$ are defined. Let $\{v_i, i\in\mathbb{N}\}$ be the eigenvectors of $\mathcal{K}^s$ for all $s\geq 0$. Let $f = \displaystyle\sum_{i=1}^{\infty}a_iv_i + f^{\perp}$ be the orthogonal decomposition with descending $|a_i|$. We prove that $\displaystyle\lim_{τ\to\infty}λ_{τ,i} = |a_i|^2$. The continuous one-parameter semigroup $\{\mathcal{K}^s: s\geq 0\}$ is equivalent, almost surely, to the classical Koopman one-parameter semigroup defined on $L^2(X,ν)$, if the dynamical system is ergodic and has invariant measure $ν$ on the phase space $X$.
format Preprint
id arxiv_https___arxiv_org_abs_2202_08755
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Bridging Koopman Operator and time-series auto-correlation based Hilbert-Schmidt operator
Zhen, Yicun
Chapron, Bertrand
Mémin, Etienne
Optimization and Control
Given a stationary continuous-time process $f(t)$, the Hilbert-Schmidt operator $A_τ$ can be defined for every finite $τ$\cite{Vautard1989SingularSA}. Let $λ_{τ,i}$ be the eigenvalues of $A_τ$ with descending order. In this article, a Hilbert space $\mathcal{H}_f$ and the (time-shift) continuous one-parameter semigroup of isometries $\mathcal{K}^s$ are defined. Let $\{v_i, i\in\mathbb{N}\}$ be the eigenvectors of $\mathcal{K}^s$ for all $s\geq 0$. Let $f = \displaystyle\sum_{i=1}^{\infty}a_iv_i + f^{\perp}$ be the orthogonal decomposition with descending $|a_i|$. We prove that $\displaystyle\lim_{τ\to\infty}λ_{τ,i} = |a_i|^2$. The continuous one-parameter semigroup $\{\mathcal{K}^s: s\geq 0\}$ is equivalent, almost surely, to the classical Koopman one-parameter semigroup defined on $L^2(X,ν)$, if the dynamical system is ergodic and has invariant measure $ν$ on the phase space $X$.
title Bridging Koopman Operator and time-series auto-correlation based Hilbert-Schmidt operator
topic Optimization and Control
url https://arxiv.org/abs/2202.08755