Decay estimates for Cayley transforms and inverses of semigroup generators via the $\mathcal{B}$-calculus

Fuente: arXiv
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Autor principal: Wakaiki, Masashi
Formato: Preprint
Publicado: 2023
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author Wakaiki, Masashi
author_facet Wakaiki, Masashi
contents Let $-A$ be the generator of a bounded $C_0$-semigroup $(e^{-tA})_{t \geq 0}$ on a Hilbert space. First we study the long-time asymptotic behavior of the Cayley transform $V_ω(A) := (A-ωI) (A+ωI)^{-1}$ with $ω>0$. We give a decay estimate for $\|V_ω(A)^nA^{-1}\|$ when $(e^{-tA})_{t \geq 0}$ is polynomially stable. Considering the case where the parameter $ω$ varies, we estimate $\|(\prod_{k=1}^n V_{ω_k}(A))A^{-1}\|$ for exponentially stable $C_0$-semigroups $(e^{-tA})_{t \geq 0}$. Next we show that if the generator $-A$ of the bounded $C_0$-semigroup has a bounded inverse, then $\sup_{t \geq 0} \|e^{-tA^{-1}} A^{-α} \| < \infty$ for all $α>0$. We also present an estimate for the rate of decay of $\|e^{-tA^{-1}} A^{-1} \|$, assuming that $(e^{-tA})_{t \geq 0}$ is polynomially stable. To obtain these results, we use operator norm estimates offered by a functional calculus called the $\mathcal{B}$-calculus.
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id arxiv_https___arxiv_org_abs_2312_05692
institution arXiv
publishDate 2023
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spellingShingle Decay estimates for Cayley transforms and inverses of semigroup generators via the $\mathcal{B}$-calculus
Wakaiki, Masashi
Functional Analysis
Numerical Analysis
Let $-A$ be the generator of a bounded $C_0$-semigroup $(e^{-tA})_{t \geq 0}$ on a Hilbert space. First we study the long-time asymptotic behavior of the Cayley transform $V_ω(A) := (A-ωI) (A+ωI)^{-1}$ with $ω>0$. We give a decay estimate for $\|V_ω(A)^nA^{-1}\|$ when $(e^{-tA})_{t \geq 0}$ is polynomially stable. Considering the case where the parameter $ω$ varies, we estimate $\|(\prod_{k=1}^n V_{ω_k}(A))A^{-1}\|$ for exponentially stable $C_0$-semigroups $(e^{-tA})_{t \geq 0}$. Next we show that if the generator $-A$ of the bounded $C_0$-semigroup has a bounded inverse, then $\sup_{t \geq 0} \|e^{-tA^{-1}} A^{-α} \| < \infty$ for all $α>0$. We also present an estimate for the rate of decay of $\|e^{-tA^{-1}} A^{-1} \|$, assuming that $(e^{-tA})_{t \geq 0}$ is polynomially stable. To obtain these results, we use operator norm estimates offered by a functional calculus called the $\mathcal{B}$-calculus.
title Decay estimates for Cayley transforms and inverses of semigroup generators via the $\mathcal{B}$-calculus
topic Functional Analysis
Numerical Analysis
url https://arxiv.org/abs/2312.05692