A few sharp estimates of harmonic functions with applications to Steklov eigenfunctions

Fuente: arXiv
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Main Authors: Wang, Xing, Zhang, Cheng
Format: Preprint
Published: 2024
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_version_ 1866913617110106112
author Wang, Xing
Zhang, Cheng
author_facet Wang, Xing
Zhang, Cheng
contents On smooth compact manifolds with smooth boundary, we first establish the sharp lower bounds for the restrictions of harmonic functions in terms of their frequency functions, by using a combination of microlocal analysis and frequency function techniques by Almgren and Garofalo-Lin. The lower bounds can be saturated by Steklov eigenfunctions on Euclidean balls and a family of symmetric warped product manifolds. Moreover, as in Sogge and Taylor, we analyze the interior behavior of harmonic functions by constructing a parametrix for the Poisson integral operator and calculate its composition with the spectral cluster. By using microlocal analysis, we obtain several sharp estimates for the harmonic functions whose traces are quasimodes on the boundary. As applications, we establish the almost-orthogonality, bilinear estimates and transversal restriction estimates for Steklov eigenfunctions, and discuss the numerical approximation of harmonic functions.
format Preprint
id arxiv_https___arxiv_org_abs_2412_13955
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A few sharp estimates of harmonic functions with applications to Steklov eigenfunctions
Wang, Xing
Zhang, Cheng
Analysis of PDEs
Numerical Analysis
Classical Analysis and ODEs
Spectral Theory
58C40, 58J50, 58J32, 65N15
On smooth compact manifolds with smooth boundary, we first establish the sharp lower bounds for the restrictions of harmonic functions in terms of their frequency functions, by using a combination of microlocal analysis and frequency function techniques by Almgren and Garofalo-Lin. The lower bounds can be saturated by Steklov eigenfunctions on Euclidean balls and a family of symmetric warped product manifolds. Moreover, as in Sogge and Taylor, we analyze the interior behavior of harmonic functions by constructing a parametrix for the Poisson integral operator and calculate its composition with the spectral cluster. By using microlocal analysis, we obtain several sharp estimates for the harmonic functions whose traces are quasimodes on the boundary. As applications, we establish the almost-orthogonality, bilinear estimates and transversal restriction estimates for Steklov eigenfunctions, and discuss the numerical approximation of harmonic functions.
title A few sharp estimates of harmonic functions with applications to Steklov eigenfunctions
topic Analysis of PDEs
Numerical Analysis
Classical Analysis and ODEs
Spectral Theory
58C40, 58J50, 58J32, 65N15
url https://arxiv.org/abs/2412.13955