Parabolic abstract evolution equations in cylindrical domains and uniformly local Sobolev spaces

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Main Author: Joly, Romain
Format: Preprint
Published: 2025
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author Joly, Romain
author_facet Joly, Romain
contents In this article, we consider parabolic equations of the type $$\partial_t u(x,t)=Δu(x,t) - Bu(x,t) + F(u(x,t))$$ where $u$ is valued in a transverse Hilbert space $Y$ and $B$ is a positive self-adjoint operator on $Y$, allowing a different diffusion mechanism in the transverse direction. We aim at considering solutions with infinite energy and we study the Cauchy problem in the uniformly local spaces associated with the norm $$\|u\|_{L^2_{\text{ul}}(\mathbb{R},Y)}= \sup_{a\in\mathbb{R}^d} \|u(x)\|_{L^2(B(a,1),Y)}.$$ For the classical parabolic equation, i.e. if $Y=\mathbb{R}$, it is known that the Cauchy problem is ill-posed in the weak version of the uniformly local spaces but well-posed in a stronger version, where additional uniform continuity is required. In this paper, we show that the linear operator $\partial^2_{xx} - B$ is not necessarily a sectorial operator in any version of the uniformly local Lebesgue space, due to the possible non-density of its domain. Then, we use the theory of parabolic abstract evolution equations to set a well-posed Cauchy problem, even in the weak version of the uniformly local space. In particular, we believe that this paper offers a new perspective on the comparison between both versions of the uniformly local spaces and also provides a new natural example of differential operators with non-dense domain.
format Preprint
id arxiv_https___arxiv_org_abs_2508_05220
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Parabolic abstract evolution equations in cylindrical domains and uniformly local Sobolev spaces
Joly, Romain
Analysis of PDEs
35A01, 35A02, 35K57, 35K58, 35K90, 47B12, 47D62
In this article, we consider parabolic equations of the type $$\partial_t u(x,t)=Δu(x,t) - Bu(x,t) + F(u(x,t))$$ where $u$ is valued in a transverse Hilbert space $Y$ and $B$ is a positive self-adjoint operator on $Y$, allowing a different diffusion mechanism in the transverse direction. We aim at considering solutions with infinite energy and we study the Cauchy problem in the uniformly local spaces associated with the norm $$\|u\|_{L^2_{\text{ul}}(\mathbb{R},Y)}= \sup_{a\in\mathbb{R}^d} \|u(x)\|_{L^2(B(a,1),Y)}.$$ For the classical parabolic equation, i.e. if $Y=\mathbb{R}$, it is known that the Cauchy problem is ill-posed in the weak version of the uniformly local spaces but well-posed in a stronger version, where additional uniform continuity is required. In this paper, we show that the linear operator $\partial^2_{xx} - B$ is not necessarily a sectorial operator in any version of the uniformly local Lebesgue space, due to the possible non-density of its domain. Then, we use the theory of parabolic abstract evolution equations to set a well-posed Cauchy problem, even in the weak version of the uniformly local space. In particular, we believe that this paper offers a new perspective on the comparison between both versions of the uniformly local spaces and also provides a new natural example of differential operators with non-dense domain.
title Parabolic abstract evolution equations in cylindrical domains and uniformly local Sobolev spaces
topic Analysis of PDEs
35A01, 35A02, 35K57, 35K58, 35K90, 47B12, 47D62
url https://arxiv.org/abs/2508.05220