Monotonicity for solutions to semilinear problems in epigraphs

Fuente: arXiv
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Autori principali: Beuvin, Nicolas, Farina, Alberto, Sciunzi, Berardino
Natura: Preprint
Pubblicazione: 2025
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author Beuvin, Nicolas
Farina, Alberto
Sciunzi, Berardino
author_facet Beuvin, Nicolas
Farina, Alberto
Sciunzi, Berardino
contents We consider positive solutions, possibly unbounded, to the semilinear equation $-Δu=f(u)$ on continuous epigraphs bounded from below. Under the homogeneous Dirichlet boundary condition, we prove new monotonicity results for $u$, when $f$ is a (locally or globally) Lipschitz-continuous function satisfying $ f(0) \geq 0$. As an application of our new monotonicity theorems, we prove some classification and/or non-existence results. To prove our results, we first establish some new comparison principles for semilinear problems on general unbounded open sets of $\mathbb{R}^N$, and then we use them to start and to complete a modified version of the moving plane method adapted to the geometry of the epigraph $Ω$. As a by-product of our analysis, we also prove some new results of uniqueness and symmetry for solutions (possibly unbounded and sign-changing) to the homogeneous Dirichlet BVP for the semilinear Poisson equation in fairly general unbounded domains.
format Preprint
id arxiv_https___arxiv_org_abs_2502_04805
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Monotonicity for solutions to semilinear problems in epigraphs
Beuvin, Nicolas
Farina, Alberto
Sciunzi, Berardino
Analysis of PDEs
We consider positive solutions, possibly unbounded, to the semilinear equation $-Δu=f(u)$ on continuous epigraphs bounded from below. Under the homogeneous Dirichlet boundary condition, we prove new monotonicity results for $u$, when $f$ is a (locally or globally) Lipschitz-continuous function satisfying $ f(0) \geq 0$. As an application of our new monotonicity theorems, we prove some classification and/or non-existence results. To prove our results, we first establish some new comparison principles for semilinear problems on general unbounded open sets of $\mathbb{R}^N$, and then we use them to start and to complete a modified version of the moving plane method adapted to the geometry of the epigraph $Ω$. As a by-product of our analysis, we also prove some new results of uniqueness and symmetry for solutions (possibly unbounded and sign-changing) to the homogeneous Dirichlet BVP for the semilinear Poisson equation in fairly general unbounded domains.
title Monotonicity for solutions to semilinear problems in epigraphs
topic Analysis of PDEs
url https://arxiv.org/abs/2502.04805