Searcharxiv⌕ Search

arXiv subjects

Seunghyeok Kim

Publications and source records attributed to Seunghyeok Kim.

29 records · Page 2Linked to original sources
arXiv2018

A compactness theorem of the fractional Yamabe problem, Part I: The non-umbilic conformal infinity

Assume that $(X, g^+)$ is an asymptotically hyperbolic manifold, $(M, [\bar{h}])$ is its conformal infinity, $ρ$ is the geodesic boundary defining function associated to $\bar{h}$ and $\bar{g} = ρ^2 g^+$. For any $γ\in (0,1)$, we prove that the solution set of the $γ$-Yamabe problem on $M$ is compact in $C^2(M)$ provided that convergence of the scalar curvature $R[g^+]$ of $(X, g^+)$ to $-n(n+1)$ is sufficiently fast as $ρ$ tends to 0 and the second fundamental form on $M$ never vanishes. Since most of the arguments in blow-up analysis performed here is irrelevant to the geometric assumption imposed on $X$, our proof also provides a general scheme toward other possible compactness theorems for the fractional Yamabe problem.

math.AP↗
arXiv2018

Asymptotic behavior of least energy solutions to the Lane-Emden system near the critical hyperbola

The Lane-Emden system is written as \begin{equation*} \begin{cases} -Δu = v^p &\text{in } Ω,\\ -Δv = u^q &\text{in } Ω,\\ u, v > 0 &\text{in } Ω,\\ u = v = 0 &\text{on } \partial Ω\end{cases} \end{equation*} where $Ω$ is a smooth bounded domain in the Euclidean space $\mathbb{R}^n$ for $n \ge 3$ and $0< p< q <\infty$. The asymptotic behavior of least energy solutions near the critical hyperbola was studied by Guerra \cite{G} when $p \geq 1$ and the domain is convex. In this paper, we cover all the remaining cases $p < 1$ and extend the results to any smooth bounded domain.

math.AP↗
arXiv2016

Minimal energy solutions to the fractional Lane-Emden system, I: Existence and singularity formation

This is the first of two papers which study asymptotic behavior of minimal energy solutions to the fractional Lane-Emden system in a smooth bounded domain $Ω$ \[(-Δ)^s u = v^p, \quad (-Δ)^s v = u^q \text{ in } Ω\quad \text{and} \quad u = v = 0 \text{ on } \pa Ω\quad \text{for } 0 < s < 1\] under the assumption that the subcritical pair $(p,q)$ approaches to the critical Sobolev hyperbola. If $p = 1$, the above problem is reduced to the subcritical higher-order fractional Lane-Emden equation with the Navier boundary condition \[(-Δ)^s u = u^{\frac{n+2s}{n-2s}-\ep} \text{ in } Ω\quad \text{and} \quad u = (-Δ)^{s \over 2} u = 0 \quad \text{for } 1 < s < 2.\] The main objective of this paper is to deduce the existence of minimal energy solutions, and to examine their (normalized) pointwise limits provided that $Ω$ is convex. As a by-product of our study, a new approach for the existence of an extremal function for the Hardy-Littlewood-Sobolev inequality is provided.

math.AP↗
arXiv2016

Existence theorems of the fractional Yamabe problem

Let $X$ be an asymptotically hyperbolic manifold and $M$ its conformal infinity. This paper is devoted to deduce several existence results of the fractional Yamabe problem on $M$ under various geometric assumptions on $X$ and $M$: Firstly, we handle when the boundary $M$ has a point at which the mean curvature is negative. Secondly, we re-encounter the case when $M$ has zero mean curvature and is either non-umbilic or umbilic but non-locally conformally flat. As a result, we replace the geometric restrictions given by González-Qing (Analysis and PDE, 2013) and González-Wang (arXiv:1503.02862) with simpler ones. Also, inspired by Marques (Comm. Anal. Geom., 2007) and Almaraz (Pacific J. Math., 2010), we study lower-dimensional manifolds. Finally, the situation when $X$ is Poincaré-Einstein, $M$ is either locally conformally flat or 2-dimensional is covered under the validity of the positive mass theorem for the fractional conformal Laplacians.

math.AP↗
arXiv2015

Classification of finite energy solutions to the fractional Lane-Emden-Fowler equations with slightly subcritical exponents

We study qualitative properties of solutions to the fractional Lane-Emden-Fowler equations with slightly subcritical exponents where the associated fractional Laplacian is defined in terms of either the spectra of Dirichlet Laplacian or the integral representation. As a consequence, we classify the asymptotic behavior of all finite energy solutions. Our method also provides a simple and unified approach to deal with the classical (local) Lane-Emden-Fowler equation for any dimension greater than 2.

math.AP↗
arXiv2015

A non-compactness result on the fractional Yamabe problem in large dimensions

Let $(X^{n+1}, g^+)$ be an $(n+1)$-dimensional asymptotically hyperbolic manifold with a conformal infinity $(M^n, [\hat{h}])$. The fractional Yamabe problem addresses to solve \[P^γ[g^+,\hat{h}] (u) = cu^{n+2γ\over n-2γ}, \quad u > 0 \quad \text{on } M\] where $c \in \mathbb{R}$ and $P^γ[g^+,\hat{h}]$ is the fractional conformal Laplacian whose principal symbol is $(-Δ)^γ$. In this paper, we construct a metric on the half space $X = \mathbb{R}^{n+1}_+$, which is conformally equivalent to the unit ball, for which the solution set of the fractional Yamabe equation is non-compact provided that $n \ge 24$ for $γ\in (0, γ^*)$ and $n \ge 25$ for $γ\in [γ^*,1)$ where $γ^* \in (0, 1)$ is a certain transition exponent. The value of $γ^*$ turns out to be approximately 0.940197.

math.AP↗
arXiv2015

On perturbations of the fractional Yamabe problem

The fractional Yamabe problem, proposed by González-Qing (2013, Anal. PDE) is a geometric question which concerns the existence of metrics with constant fractional scalar curvature. It extends the phenomena which were discovered in the classical Yamabe problem and the boundary Yamabe problem to the realm of nonlocal conformally invariant operators. We investigate a non-compactness property of the fractional Yamabe problem by constructing bubbling solutions to its small perturbations.

math.AP↗
arXiv2014

Qualitative properties of multi-bubble solutions for nonlinear elliptic equations involving critical exponents

The objective of this paper is to obtain qualitative characteristics of multi-bubble solutions to the Lane-Emden-Fowler equations with slightly subcritical exponents given any dimension $n \ge 3$. By examining the linearized problem at each $m$-bubble solution, we provide a number of estimates on the first $(n+2)m$-eigenvalues and their corresponding eigenfunctions. Specifically, we present a new proof of the classical theorem due to Bahri-Li-Rey (Calc. Var. Partial Differential Equations 3 (1995) 67-93) which states that if $n \ge 4$, then the Morse index of a multi-bubble solution is governed by a certain symmetric matrix whose component consists of a combination of Green's function, the Robin function, and their first and second derivatives. Our proof also allows us to handle the intricate case $n = 3$.

math.AP↗
arXiv2013

Supercritical problems in domains with thin toroidal holes

In this paper we study the Lane-Emden-Fowler equation $$(P)_ε \{Δu+|u|^{q-2}u=0 \ \hbox{in}\ \mathcal D_ε, u=0 \ \hbox{on}\ \partial\mathcal D_ε.$$ Here $\mathcal D_ε= \mathcal D \setminus \{x \in \mathcal D \ : \ \mathrm{dist}(x,Γ_\ell)\le ε\}$, $\mathcal D$ is a smooth bounded domain in $\mathbb{R}^N$, $Γ_\ell$ is an $\ell-$dimensional closed manifold such that $Γ_\ell \subset \mathcal D$ with $1\le \ell \le N-3$ and $q={2(N-\ell)\over N-\ell-2}$. We prove that, under some symmetry assumptions, the number of sign changing solutions to $(P)_ε$ increases as $ε$ goes to zero.

math.AP↗
arXiv2013

Boundary towers of layers for some supercritical problems

We show that in some suitable torus-like domains D some supercritical elliptic problems have an arbitrary large number of sign-changing solutions with alternate positive and negative layers which concentrate at different rates along a k-dimensional submanifold of the boundary of D as p approaches 2*_{N,K} from below.

math.AP↗