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Addolorata Salvatore

Publications and source records attributed to Addolorata Salvatore.

10 recordsLinked to original sources
arXiv2025

A dichotomy result for a modified Schr\"odinger equations on unbounded domains

This article aims to investigate the existence of bounded positive solutions of problem \[ (P)\qquad \left\{ \begin{array}{ll} - {\rm div} (a(x,u,\nabla u)) + A_t(x,u,\nabla u) = g(x,u) &\hbox{in $\Omega$,}\\ u\ = \ 0 & \hbox{on $\partial\Omega$,} \end{array}\right.\] with $A_t(x,t,\xi) = \frac{\partial A}{\partial t}(x,t,\xi)$, $a(x,t,\xi) = \nabla_\xi A(x,t,\xi)$ for a given $A(x,t,\xi)$ which grows as $|\xi|^p + |t|^p$ , $p > 1$, where $\Omega \subseteq \mathbb{R}^N$, $N \ge 2$, is an open connected domain with Lipschitz boundary and infinite Lebesgue measure, eventually $\Omega = \mathbb{R}^N$, which generalizes the modified Schr\"odinger equation \[ - {\rm div} ((A^*_1(x) + A^*_2(x)|u|^{s}) \nabla u) + \frac{s}2 A^*_2(x)\ |u|^{s - 2} u\ |\nabla u|^2 + u\ =\ |u|^{\mu-2}u \quad\hbox{in $\mathbb{R}^3$.} \] Under suitable assumptions on $A(x,t,\xi)$ and $g(x,t)$, problem $(P)$ has a variational structure. Then, even in lack of radial symmetry hypotheses, one bounded positive solution of $(P)$ can be found by passing to the limit on a sequence $(u_k)_k$ of bounded solutions on bounded domains. Furthermore, if stronger hypotheses are satisfied, either such a solution is nontrivial or a constant $\bar{\lambda} > 0$ and a sequence of points $(y_k)_k \subset \mathbb{R}^N$ exist such that \[ |y_k| \to +\infty\qquad \hbox{and}\qquad \int_{B_1(y_k)} |u_k|^p dx \ge \bar{\lambda}\quad \hbox{for all $k \ge 1$.} \]

math.AP↗
arXiv2024

Existence results for a borderline case of a class of p-Laplacian problems

The aim of this paper is investigating the existence of at least one nontrivial bounded solution of the new asymptotically ``linear'' problem \[ \left\{ \begin{array}{ll} - {\rm div} \left[\left(A_0(x) + A(x) |u|^{ps}\right) |\nabla u|^{p-2} \nabla u\right] + s\ A(x) |u|^{ps-2} u\ |\nabla u|^p &\\ \qquad\qquad\qquad =\ \mu |u|^{p (s + 1) -2} u + g(x,u) & \hbox{in $\Omega$,}\\ u = 0 & \hbox{on $\partial{\Omega}$,} \end{array}\right.\] where $\Omega$ is a bounded domain in $\mathbb{R}^N$, $N \ge 2$, $1 < p < N$, $s > 1/p$, both the coefficients $A_0(x)$ and $A(x)$ are in $L^\infty(\Omega)$ and far away from 0, $\mu \in \mathbb{R}$, and the ``perturbation'' term $g(x,t)$ is a Carath\'{e}odory function on $\Omega \times \mathbb{R}$ which grows as $|t|^{r-1}$ with $1\le r < p (s + 1)$ and is such that $g(x,t) \approx \nu |t|^{p-2} t$ as $t \to 0$. By introducing suitable thresholds for the parameters $\nu$ and $\mu$, which are related to the coefficients $A_0(x)$, respectively $A(x)$, under suitable hypotheses on $g(x,t)$, the existence of a nontrivial weak solution is proved if either $\nu$ is large enough with $\mu$ small enough or $\nu$ is small enough with $\mu$ large enough. Variational methods are used and in the first case a minimization argument applies while in the second case a suitable Mountain Pass Theorem is used.

math.AP↗
arXiv2023

Radial bounded solutions for modified Schrödinger equations

We study the quasilinear equation $(P)\qquad - {\rm div} (a(x,u,\nabla u)) +A_t(x,u,\nabla u) + |u|^{p-2}u\ =\ g(x,u) \qquad \hbox{in $\R^N$,} $ with $N\ge 3$ and $p > 1$. Here, we suppose $A : \R^N \times \R \times \R^N \to \R$ is a given ${C}^{1}$-Carathéodory function which grows as $|ξ|^p$ with $A_t(x,t,ξ) = \frac{\partial A}{\partial t}(x,t,ξ)$, $a(x,t,ξ) = \nabla_ξA(x,t,ξ)$ and $g(x,t)$ is a given Carathéodory function on $\R^N \times \R$ which grows as $|ξ|^q$ with $1<q<p$. Suitable assumptions on $A(x,t,ξ)$ and $g(x,t)$ set off the variational structure of $(P)$ and its related functional $\J$ is $C^1$ on the Banach space $X = W^{1,p}(\R^N) \cap L^\infty(\R^N)$. In order to overcome the lack of compactness, we assume that the problem has radial symmetry, then we look for critical points of $\J$ restricted to $X_r$, subspace of the radial functions in $X$. Following an approach that exploits the interaction between the intersection norm in $X$ and the norm on $W^{1,p}(\R^N)$, we prove the existence of at least two weak bounded radial solutions of $(P)$, one positive and one negative, by applying a generalized version of the Minimum Principle.

math.AP↗
arXiv2023

On existence and multiplicity of solutions for generalized (p, q)-Laplacian equations on unbounded domains

This paper deals with the existence and multiplicity of solutions for the generalized $(p, q)$-Laplacian equation \begin{align*} &-{\text{ div}}(A(x, u)|\nabla u|^{p-2}\nabla u) +\frac1p A_t(x, u)|\nabla u|^p -{\text{ div}}(B(x, u)|\nabla u|^{q-2}\nabla u) \\ &\quad\qquad+\frac1q B_t(x, u)|\nabla u|^q + V(x)|u|^{p-2} u+ W(x)|u|^{q-2} u= g(x, u)\quad\qquad\mbox{ in } \mathbb{R}^N, \end{align*} where $1<q\le p< N$, $A, B:\mathbb{R}^N\times\mathbb{R}\to\mathbb{R}$ are suitable $C^1$ Carathéodory functions with $A_t(x, u)=\frac{\partial A}{\partial t}(x, u), B_t(x, u)=\frac{\partial B}{\partial t}(x, u)$, $V, W:\mathbb{R}^N\to\mathbb{R}$ are proper ``weight functions" and $g:\mathbb{R}^N\times\mathbb{R}\to\mathbb{R}$ is a Carathéodory map. Notwithstanding the occurrence of some coefficients which rely upon the solution itself makes the use of variational techniques more challenging, under suitable assumptions on the involved functions, we are able to exploit the variational nature of our problem. In particular, the existence of a nontrivial solution is derived via a generalized version of the Ambrosetti-Rabinowitz Mountain Pass Theorem, based on a weaker version of the classical Cerami-Palais-Smale condition. Finally, the multiplicity result, which is thoroughly new also even in the simpler case $q=p$, is gained under symmetry assumptions and a sharp decomposition of the ambient space.

math.AP↗
arXiv2022

Bounded solutions for quasilinear modified Schrödinger equations

In this paper we establish a new existence result for the quasilinear elliptic problem \[ -{\rm div}(A(x,u)|\nabla u|^{p-2}\nabla u) +\frac1p A_t(x,u)|\nabla u|^p + V(x)|u|^{p-2} u = g(x,u)\quad\mbox{ in } \mathbb{R}^N, \] with $N\ge 2$, $p>1$ and $V:\mathbb{R}^N\to\mathbb{R}$ suitable measurable positive function, which generalizes the modified Schrödinger equation. Here, we suppose that $A:\mathbb{R}^N\times\mathbb{R}\rightarrow\mathbb{R}$ is a $\mathcal{C}^{1}$-Carathéodory function such that $A_t(x,t) = \frac{\partial A}{\partial t} (x,t)$ and a given Carathéodory function $g:\mathbb{R}^N\times\mathbb{R}\rightarrow\mathbb{R}$ has a subcritical growth and satisfies the Ambrosetti-Rabinowitz condition. Since the coefficient of the principal part depends also on the solution itself, we study the interaction of two different norms in a suitable Banach space so to obtain a "good" variational approach. Thus, by means of approximation arguments on bounded sets we can state the existence of a nontrivial weak bounded solution.

math.AP↗
arXiv2022

Existence and multiplicity results for a class of coupled quasilinear elliptic systems of gradient type

The aim of this paper is investigating the existence of one or more weak solutions of the coupled quasilinear elliptic system of gradient type \[ (P)\qquad \left\{ \begin{array}{ll} - {\rm div} (A(x, u)\vert\nabla u\vert^{p_1 -2} \nabla u) + \frac{1}{p_1}A_u (x, u)\vert\nabla u\vert^{p_1} = G_u(x, u, v) &\hbox{ in $Ω$,}\\[5pt] - {\rm div} (B(x, v)\vert\nabla v\vert^{p_2 -2} \nabla v) +\frac{1}{p_2}B_v(x, v)\vert\nabla v\vert^{p_2} = G_v\left(x, u, v\right) &\hbox{ in $Ω$,}\\[5pt] u = v = 0 &\hbox{ on $\partialΩ$,} \end{array} \right. \] where $Ω\subset \mathbb{R}^N$ is an open bounded domain, $p_1$, $p_2 > 1$ and $A(x,u)$, $B(x,v)$ are $\mathcal{C}^1$-Carathéodory functions on $Ω\times \mathbb{R}$ with partial derivatives $A_u(x,u)$, respectively $B_v(x,v)$, while $G_u(x,u,v)$, $G_v(x,u,v)$ are given Carathéodory maps defined on $Ω\times \mathbb{R}\times \mathbb{R}$ which are partial derivatives of a function $G(x,u,v)$. We prove that, even if the coefficients make the variational approach more difficult, under suitable hypotheses functional $\cal{J}$, related to problem $(P)$, admits at least one critical point in the ''right'' Banach space $X$. Moreover, if $\cal{J}$ is even, then $(P)$ has infinitely many weak bounded solutions. The proof, which exploits the interaction between two different norms, is based on a weak version of the Cerami-Palais-Smale condition, a ''good'' decomposition of the Banach space $X$ and suitable generalizations of the Ambrosetti-Rabinowitz Mountain Pass Theorems.

math.AP↗
arXiv2019

Multiple solutions for some symmetric supercritical problems

The aim of this paper is investigating the existence of one or more critical points of a family of functionals which generalizes the model problem \[ \bar J(u)\ =\ \frac1p\ \int_Ω\bar A(x,u)|\nabla u|^p dx - \int_ΩG(x,u) dx \] in the Banach space $X = W^{1,p}_0(Ω)\cap L^\infty(Ω)$, where $Ω\subset {\mathbb R}^N$ is an open bounded domain, $1 < p < N$ and the real terms $\bar A(x,t)$ and $G(x,t)$ are $C^1$ Carathéodory functions on $Ω\times {\mathbb R}$. We prove that, even if the coefficient $\bar A(x,t)$ makes the variational approach more difficult, if it satisfies ``good'' growth assumptions then at least one critical point exists also when the nonlinear term $G(x,t)$ has a suitable supercritical growth. Moreover, if the functional is even, it has infinitely many critical levels. The proof, which exploits the interaction between two different norms on $X$, is based on a weak version of the Cerami-Palais-Smale condition and a suitable intersection lemma which allow us to use a Mountain Pass Theorem.

math.AP↗
arXiv2019

Existence of radial bounded solutions for some quasilinear elliptic equations in R^N

We study the quasilinear equation \[(P)\qquad - {\rm div} (A(x,u) |\nabla u|^{p-2} \nabla u) + \frac1p\ A_t(x,u) |\nabla u|^p + |u|^{p-2}u\ =\ g(x,u) \qquad \hbox{in ${\mathbb R}^N$,} \] with $N\ge 3$, $p > 1$, where $A(x,t)$, $A_t(x,t) = \frac{\partial A}{\partial t}(x,t)$ and $g(x,t)$ are Carathéodory functions on ${\mathbb R}^N \times {\mathbb R}$. Suitable assumptions on $A(x,t)$ and $g(x,t)$ set off the variational structure of $(P)$ and its related functional ${\cal J}$ is $C^1$ on the Banach space $X = W^{1,p}({\mathbb R}^N) \cap L^\infty({\mathbb R}^N)$. In order to overcome the lack of compactness, we assume that the problem has radial symmetry, then we look for critical points of ${\cal J}$ restricted to $X_r$, subspace of the radial functions in $X$. Following an approach which exploits the interaction between $\|\cdot\|_X$ and the norm on $W^{1,p}({\mathbb R}^N)$, we prove the existence of at least one weak bounded radial solution of $(P)$ by applying a generalized version of the Ambrosetti-Rabinowitz Mountain Pass Theorem.

math.AP↗