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Disson dos Prazeres

Publications and source records attributed to Disson dos Prazeres.

11 recordsLinked to original sources
arXiv2026

Strong maximum principle for fully nonlinear nonlocal problems

In this paper, we study solvability and qualitative properties of nonnegative solutions for a sublinear nonlocal problem with fully nonlinear structure in the form $$ \mathcal{M}^{\pm}[u]+a(x)u^{q}(x)=0 \; \text{ in }\Omega,\qquad u\geq 0 \; \text{ in }\Omega. $$ Here $\Omega \subset \mathbb{R}^n$ is a bounded $C^{1,1}$ convex domain, $\mathcal{M}^{ \pm}$ stands for nonlocal Pucci extremal operators defined in a class $\mathcal{L}_*$ of homogeneous kernels, $q\in(0,1)$, and $a$ is a possibly sign-changing weight. We introduce a new nonlocal hypothesis on the negative part of the solution outside the domain, which together with the negative part of the potential, influences the formation of dead cores and cannot be removed. Our approach relies on uniform bounds from below of the maximum of nontrivial solutions through Liouville theorems, and on a Hopf lemma for viscosity solutions driven by fully nonlinear operators, which we also prove.

math.AP↗
arXiv2025

A two-phase quenching-type problem for the p-Laplacian

We study minimizers of non-differentiable functionals of the Alp-Phillips type with two-phases for the $p$-Laplacian , focusing on the geometric and analytical properties of free boundaries. The main result establishes finite $(n-1)$-dimensional Hausdorff measure estimates, achieved through optimal gradient decay estimates, a $BV$-inequality and the known classifications of blow-up profiles of the linear case.

math.AP↗
arXiv2025

Improved regularity for a nonlocal dead-core problem

We obtain improved regularity results for solutions to a nonlocal dead-core problem at branching points. Our approach, which does not rely on the maximum principle, introduces a new strategy for analyzing two-phase problems within the local framework, an area that remains largely unexplored.

math.AP↗
arXiv2024

Sharp and improved regularity estimates for weighted quasilinear elliptic equations of $p-$Laplacian type and applications

In this manuscript, we obtain sharp and improved regularity estimates for weak solutions of weighted quasilinear elliptic models of Hardy-H\'{e}non-type, featuring an explicit regularity exponent depending only on universal parameters. Our approach is based on geometric tangential methods and uses a refined oscillation mechanism, compactness, and scaling techniques. In some specific scenarios, we establish higher regularity estimates and non-degeneracy properties, providing further geometric insights into such solutions. Our regularity estimates both enhance and, to some extent, extend the results arising from the $C^{p^{\prime}}$ conjecture for the $p$-Laplacian with a bounded source term. As applications of our results, we address some Liouville-type results for our class of equations. Finally, our results are noteworthy, even in the simplest model case governed by the $p$-Laplacian with regular coefficients: $$ \mathrm{div}\left( |\nabla u|^{p-2}\mathfrak{A}(|x|) \nabla u\right) = |x|^{\alpha}u_+^m(x) \quad \text{in} \quad B_1 $$ under suitable assumptions on the data, with possibly singular weight $\mathfrak{h}(|x|) = |x|^{\alpha}$, which includes the Matukuma and Batt-Faltenbacher-Horst's equations as toy models.

math.AP↗
arXiv2023

On fractional quasilinear equations with elliptic degeneracy

In this work, we present a systematic approach to investigate the existence, multiplicity, and local gradient regularity of solutions for nonlocal quasilinear equations with local gradient degeneracy. Our method involves an interactive geometric argument that interplays with uniqueness property for the corresponding homogeneous problem, leading with gradient Hölder regularity estimates. This approach is intrinsically developed for nonlocal scenarios, where uniqueness holds for the local homogeneous problem. We illustrate our results by showing classes of exterior data that exhibit multiple solutions, while also highlighting relevant cases where uniqueness is confirmed.

math.AP↗
arXiv2023

Fundamental solutions and critical Lane-Emden exponents for nonlinear integral operators in cones

In this article we study the fundamental solutions or "$\alpha$-harmonic functions" for some nonlinear positive homogeneous nonlocal elliptic problems in conical domains, such as \begin{eqnarray*}\label{ecbir1a1} {\mathcal F }(u)=0\ \ \hbox{in} \ \ \mathcal{C}_\omega,\quad u=0\ \ \hbox{in} \ \ \mathbb{R}^n\setminus \mathcal{C}_\omega ,\ \ \end{eqnarray*} where $\omega$ is a proper $C^2$ domain in $S^{N-1}$ for $ N\geq 2$, $\mathcal{C}_\omega:=\{x\,:\,x\neq 0, {|x|^{-1}}x\in \omega\}$ is the cone-like domain related to $\omega$, and ${\mathcal F }$ is an extremal fully nonlinear integral operator. We prove the existence of two fundamental solutions that are homogeneous and do not change signs in the cone; one is bounded at the origin and the other at infinity. As an application, we use the fundamental solutions obtained to prove Liouville type theorems in cones for supersolutions of the Lane-Emden-Fowler equation in the form \begin{eqnarray*}\label{eq 0.2} {\mathcal F }(u)+u^p = 0\ \ \hbox{in} \ \ \mathcal{C}_\omega, \quad u=0\ \ \hbox{in} \ \ \mathbb{R}^n\setminus \mathcal{C}_\omega.\ \ \end{eqnarray*} We also prove a generalized Hopf type lemma in domains with corners. Most of our results are new even when ${\mathcal F }$ is the fractional Laplacian operator.

math.AP↗
arXiv2022

Cordes-Nirenberg type results for nonlocal equations with deforming kernels

We derive Cordes-Nirenberg type results for nonlocal elliptic integro-differential equations with deforming kernels comparable to sections of a convex solution of a Monge-Amp\`ere equation. Under a natural integrability assumption on the Monge-Amp\`ere solution, we prove a stability lemma allowing the ellipticity class to vary. Using a compactness method, we then derive H\"older regularity estimates for the gradient of the solutions.

math.AP↗
arXiv2020

A note on the density of the partial regularity result in the class of viscosity solutions

We establish the density of the partial regularity result in the class of continuous viscosity solutions. Given a fully nonlinear equation, we prove the existence of a sequence entitled to the partial regularity result, approximating its solutions. Distinct conditions on the operator driving the equation lead to density in different topologies. Our findings include applications to inhomogeneous problems, with variable-coefficients models.

math.AP↗
arXiv2020

Non-existence of dead cores in fully nonlinear elliptic models

We investigate non-existence of nonnegative dead-core solutions for the problem $$|Du|^γF(x, D^2u)+a(x)u^q = 0 \quad \mbox{in} \quad Ω, \quad u=0 \quad \mbox{ on } \quad \partialΩ.$$ Here $Ω\subset \mathbb{R}^N$ is a bounded smooth domain, $F$ is a fully nonlinear elliptic operator, $a: Ω\to \mathbb{R}$ is a sign-changing weight, $γ\geq 0$, and $0<q<γ+1$. We show that this problem has no non-trivial dead core solutions if either $q$ is close enough to $γ+1$ or the negative part of $a$ is sufficiently small. In addition, we obtain the existence and uniqueness of a positive solution under these conditions on $q$ and $a$. Our results extend previous ones established in the semilinear case, and are new even for the simple model $|D u(x)|^γ \mathrm{Tr}(\mathrm{A}(x) D^2 u(x)) + a(x)u^{q}(x) = 0$, where $\mathrm{A} \in C^0(Ω;Sym(N))$ is a uniformly elliptic and non-negative matrix.

math.AP↗
arXiv2015

Cavity problems in discontinuous media

We study cavitation type equations, $\text{div}(a_{ij}(X) \nabla u) \sim δ_0(u)$, for bounded, measurable elliptic media $a_{ij}(X)$. De Giorgi-Nash-Moser theory assures that solutions are $α$-Hölder continuous within its set of positivity, $\{u>0\}$, for some exponent $α$ strictly less than one. Notwithstanding, the key, main result proven in this paper provides a sharp Lipschitz regularity estimate for such solutions along their free boundaries, $\partial \{u>0 \}$. Such a sharp estimate implies geometric-measure constrains for the free boundary. In particular, we show that the non-coincidence $\{u>0\}$ set has uniform positive density and that the free boundary has finite $(n- ς)$-Hausdorff measure, for a universal number $0< ς\le 1$.

math.AP↗