On the M.Kac problem with augmented data

Fuente: arXiv
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Autori principali: Belishev, M. I., Vakulenko, A. F.
Natura: Preprint
Pubblicazione: 2024
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author Belishev, M. I.
Vakulenko, A. F.
author_facet Belishev, M. I.
Vakulenko, A. F.
contents Let $Ω$ be a bounded plane domain. As is known, the spectrum $0<λ_1<λ_2\leqslant\dots$ of its Dirichlet Laplacian $L=-Δ{\upharpoonright}[H^2(Ω)\cap H^1_0(Ω)]$ does not determine $Ω$ (up to isometry). By this, a reasonable version of the M.Kac problem is to augment the spectrum with relevant data that provide the determination. To give the spectrum is to represent $L$ in the form $\tilde L=ΦLΦ^*={\rm diag\,}\{λ_1,λ_2,\dots\}$ in the space ${\bf l}_2$, where $Φ:L_2(Ω)\to{\bf l}_2$ is the Fourier transform. Let ${\mathscr K}=\{h\in L_2(Ω)\,|\,\,Δh=0\,\,{\rm in}\,\,Ω\}$ be the harmonic function subspace, $\tilde{\mathscr K}=Φ{\mathscr K}\subset{\bf l}_2$. We show that, in a generic case, the pair $\tilde L,\tilde {\mathscr K}$ determines $Ω$ up to isometry, what holds not only for the plain domains (drums) but for the compact Riemannian manifolds of arbitrary dimension, metric, and topology. Thus, the subspace $\tilde{\mathscr K}\subset{\bf l}_2$ augments the spectrum, making the problem uniquely solvable.
format Preprint
id arxiv_https___arxiv_org_abs_2405_16629
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the M.Kac problem with augmented data
Belishev, M. I.
Vakulenko, A. F.
Mathematical Physics
47Axx, 47B25, 35R30
Let $Ω$ be a bounded plane domain. As is known, the spectrum $0<λ_1<λ_2\leqslant\dots$ of its Dirichlet Laplacian $L=-Δ{\upharpoonright}[H^2(Ω)\cap H^1_0(Ω)]$ does not determine $Ω$ (up to isometry). By this, a reasonable version of the M.Kac problem is to augment the spectrum with relevant data that provide the determination. To give the spectrum is to represent $L$ in the form $\tilde L=ΦLΦ^*={\rm diag\,}\{λ_1,λ_2,\dots\}$ in the space ${\bf l}_2$, where $Φ:L_2(Ω)\to{\bf l}_2$ is the Fourier transform. Let ${\mathscr K}=\{h\in L_2(Ω)\,|\,\,Δh=0\,\,{\rm in}\,\,Ω\}$ be the harmonic function subspace, $\tilde{\mathscr K}=Φ{\mathscr K}\subset{\bf l}_2$. We show that, in a generic case, the pair $\tilde L,\tilde {\mathscr K}$ determines $Ω$ up to isometry, what holds not only for the plain domains (drums) but for the compact Riemannian manifolds of arbitrary dimension, metric, and topology. Thus, the subspace $\tilde{\mathscr K}\subset{\bf l}_2$ augments the spectrum, making the problem uniquely solvable.
title On the M.Kac problem with augmented data
topic Mathematical Physics
47Axx, 47B25, 35R30
url https://arxiv.org/abs/2405.16629