The paper provides an extension, to fractional order Sobolev spaces, of the classical result of Murat and Brezis which states that the positive cone of elements in $H^{-1}(Ω)$ compactly embeds in $W^{-1,q}(Ω)$, for every $q < 2$ and for any open and bounded set $Ω$ with Lipschitz boundary. In particular, our proof contains the classical result. Several new analysis tools are developed during the course of the proof to our main result which are of wider interest. Subsequently, we apply our results to the convergence of convex sets and establish a fractional version of the Mosco convergence result of Boccardo and Murat. We conclude with an application of this result to quasi-variational inequalities.
In this paper we extend the well-known concentration -- compactness principle for the Fractional Laplacian operator in unbounded domains. As an application we show sufficient conditions for the existence of solutions to some critical equations involving the fractional $p-$laplacian in the whole ${\mathbb R}^n$.
The Aubin-Lions lemma and its variants play crucial roles for the existence of weak solutions of nonlinear evolutionary PDEs. In this paper, we aim to develop some compactness criteria that are analogies of the Aubin--Lions lemma for the existence of weak solutions to time fractional PDEs. We first define the weak Caputo derivatives of order $γ\in (0,1)$ for functions valued in general Banach spaces, consistent with the traditional definition if the space is $\mathbb{R}^d$ and functions are absolutely continuous. Based on a Volterra type integral form, we establish some time regularity estimat…
A Global Compactness type result for Palais-Smale sequences in fractional Sobolev spaces
我们推广了M. Struwe（Math. Z，1984）推广到任何分数索伯列夫空间$\dot{H}^s(Ω)$，其中$0<s<N/2$和$Ω\subset \mathbb{R}^N$是具有光滑边界的有界域.这个证明是P. Gerard所谓的Profile Decomposition（ESAIM：Control，Optimization and Calculus of Variations，1998）的一个简单的直接结果。
Improved Sobolev embeddings, profile decomposition, and concentration-compactness for fractional Sobolev spaces
在H^s空间中得到了一个改进的涉及Morrey范数的Sobolev不等式.这种改进产生了一个直接的证明的存在性的优化和紧凑的对称性的优化序列通常的Sobolev嵌入。更一般地说，它允许使用[K]中开发的位错空间的抽象方法导出[P. Gerard，ESAIM 1998]中获得的H^s中的轮廓分解的替代的、更透明的证明。Tintarev & K. H. Fieseler，Imperial College Press 2007]。我们还直接分析了Sobolev嵌入紧性的局部缺陷。Lions，Rev. Mat. Iberoamericana 1985]。作为模型应用，我们研究了一类次临界问题的渐近极限，得到了当s为整数（[O. Rey，Mandarin pta math.1989; Z.- C. Han，Ann. Inst. H.庞加莱肛门。Non Lineaire 1991]，[K. S. Chou & D. Geng，微分积分方程2000]）。
This paper is devoted to establishing the compactness and existence results of the solutions to the prescribing fractional $Q$-curvatures problem of order $2σ$ on $n$-dimensional standard sphere when $ n-2σ=2$, $σ=1+m/2,$ $m\in \mathbb{N}_{+}.$ The compactness results are novel and optimal. In addition, we prove a degree-counting formula of all solutions to achieve the existence. From our results, we can know where blow up occur. Furthermore, the sequence of solutions that blow up precisely at any finite distinct location can be constructed. It is worth noting that our results include the case…
In this paper we study the problem of prescribing fractional $Q$-curvature of order $2σ$ for a conformal metric on the standard sphere $\Sn$ with $σ\in (0,n/2)$ and $n\geq2$. Compactness and existence results are obtained in terms of the flatness order $β$ of the prescribed curvature function $K$. Making use of integral representations and perturbation result, we develop a unified approach to obtain these results when $β\in [n-2σ,n)$ for all $σ\in (0,n/2)$. This work generalizes the corresponding results of Jin-Li-Xiong [Math. Ann. 369: 109--151, 2017] for $β\in (n-2σ,n)$.
In this paper we prove compact embedding of a subspace of the fractional Orlicz-Sobolev space $W^{s, G}\left(\mathbb{R}^{N}\right)$ consisting of radial functions, our target embedding spaces are of Orlicz type. Also, we prove a Lions and Lieb type results for $W^{s,G}\left(\mathbb{R}^{N}\right)$ that works together in a particular way to get a sequence whose the weak limit is nontrivial. As an application, we study the existence of solutions to Quasilinear elliptic problems in the whole space $\mathbb{R}^N$ involving the fractional $g-$Laplacian operator, where the conjugated function $\widet…
Infinitely many solutions for $p$-fractional Choquard type equations involving general nonlocal nonlinearities with critical growth via the concentration compactness method
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 i…
Concentration-compactness principle for nonlocal scalar field equations with critical growth
本文的目的是研究齐次分数索伯列夫空间$\mathcal{D}^{s,2} (\mathbb{R}^N)$的集中紧性原理作为应用，我们建立了分数标量场方程$(-Δ)^{s} u = f(x,u)$的拉格朗日量的Palais-Smale紧性。此外，使用基于$\mathcal{D}^{s,2}(\mathbb{R}^N),$的分析框架，我们获得了在临界增长范围内的广泛的一类非线性基态解的存在性。
The present paper studies the existence of weak solutions for the following type of non-homogeneous system of equations \begin{equation*} (S) \left\{\begin{aligned} (-Δ)^{s_1}_{p_1} u &=u|u|^{α-1}|v|^{β+1}+f_1(x) \,\mbox{ in }\, Ω, \\ (-Δ)^{s_2}_{p_2} v &=|u|^{α+1}v|v|^{β-1}+f_2(x) \,\mbox{ in }\, Ω, \\ u=v &= 0 \,\mbox{ in }\, \mathbb{R}^N \setminus Ω, \\ \end{aligned} \right. \end{equation*} where $Ω\subset \mathbb{R}^N$ is smooth bounded domain, $s_1,s_2 \in (0,1)$, $1<p_1,p_2<\infty$, $N>\max\{p_1s_1,p_2s_2\}$, $α>-1$ and $β>-1$. We employ the variational techniques where the associated en…
This paper addresses the approximation of fractional harmonic maps. Besides a unit-length constraint, one has to tackle the difficulty of nonlocality. We establish weak compactness results for critical points of the fractional Dirichlet energy on unit-length vector fields. We devise and analyze numerical methods for the approximation of various partial differential equations related to fractional harmonic maps. The compactness results imply the convergence of numerical approximations. Numerical examples on spin chain dynamics and point defects are presented to demonstrate the effectiveness of …
Critical fractional $p$-Hardy Sobolev equations: Global compactness and multiplicity of positive solutions
Indian Institute of Science Education and Research Pune（印度科学教育研究所浦那分校）；Gandhi Institute of Technology and Management (GITAM) University（甘地科技与管理大学）；Krea University（克雷亚大学）
We consider the fractional critical Schr{ö}dinger equation (FCSE) \begin{align*} \slaplace{u}-\abs{u}^{2^{\ast}_{s}-2}u=0, \end{align*} where $u \in \dot H^s( \R^N)$, $N\geq 2$, $0<s<1$ and $2^{\ast}_{s}=\frac{2N}{N-2s}$. By virtue of the mini-max theory and the concentration compactness principle with the equivariant group action, we obtain the new type of non-radial, sign-changing solutions of (FCSE) in the energy space $\dot H^s(\R^N)$. The key component is that we use the equivariant group to partion $\dot H^s(\R^N)$ into several connected components, then combine the concentration compact…
In this paper, we are devoted to establishing the compactness and existence results of the solutions to the fractional Nirenberg problem for $n=3,$ $σ=1/2,$ when the prescribing $σ$-curvature function satisfies the $(n-2σ)$-flatness condition near its critical points. The compactness results are new and optimal. In addition, we obtain a degree-counting formula of all solutions. From our results, we can know where blow up occur. Moreover, for any finite distinct points, the sequence of solutions that blow up precisely at these points can be constructed. We extend the results of Li in \cite[CPAM…
We prove the existence of the set of ground states in a suitable energy space $Σ^s=\{u: \int_{\mathbb{R}^N} \bar{u}(-Δ+m^2)^s u+V |u|^2<\infty\}$, $s\in (0,\frac{N}{2})$ for the mass-subcritical nonlinear fractional Hartree equation with unbounded potentials. As a consequence we obtain, as a priori result, the orbital stability of the set of standing waves. The main ingredient is the observation that $Σ^s$ is compactly embedded in $L^2$. This enables us to apply the concentration compactness argument in the works of Cazenave-Lions and Zhang, namely, relative compactness for any minimizing sequ…
$H$-convergence and $Γ$-convergence in the Riesz fractional setting: the nonlinear case
Scuola Internazionale Superiore di Studi Avanzati (SISSA)（高等高级研究所）；Università degli Studi dell’Aquila（阿奎拉大学）；Università del Salento（萨伦托大学）；Politecnico di Milano（米兰理工大学）；Università di Padova（帕多瓦大学）
We study the compactness properties of metrics of prescribed fractional $Q$-curvature of order $3$ in $\R^3$. We will use an approach inspired from conformal geometry, seeing a metric on a subset of $\R^3$ as the restriction of a metric on $\R^4_+$ with vanishing fourth-order $Q$-curvature. We will show that a sequence of such metrics with uniformly bounded fractional $Q$-curvature can blow up on a large set (roughly, the zero set of the trace of a nonpositive biharmonic function $Φ$ in $\R^4_+$), in analogy with a $4$-dimensional result of Adimurthi-Robert-Struwe, and construct examples of su…
In this paper we study localization properties of the Riesz $s$-fractional gradient $D^s u$ of a vectorial function $u$ as $s \nearrow 1$. The natural space to work with $s$-fractional gradients is the Bessel space $H^{s,p}$ for $0 < s < 1$ and $1 < p < \infty$. This space converges, in a precise sense, to the Sobolev space $W^{1,p}$ when $s \nearrow 1$. We prove that the $s$-fractional gradient $D^s u$ of a function $u$ in $W^{1,p}$ converges strongly to the classical gradient $Du$. We also show a weak compactness result in $W^{1,p}$ for sequences of functions $u_s$ with bounded $L^p$ norm of…
We extend classical results on variational inequalities with convex sets with gradient constraint to a new class of fractional partial differential equations in a bounded domain with constraint on the distributional Riesz fractional gradient, the $σ$-gradient ($0<σ<1$). We establish continuous dependence results with respect to the data, including the threshold of the fractional $σ$-gradient. Using these properties we give new results on the existence to a class of quasi-variational variational inequalities with fractional gradient constraint via compactness and via contraction arguments. Usin…
On a two-dimensional Riemannian manifold without boundary we consider the variational limit of a family of functionals given by the sum of two terms: a Ginzburg-Landau and a perimeter term. Our scaling allows low-energy states to be described by an order parameter which can have finitely many point singularities (vortex-like defects) of (possibly) fractional-degree connected by line discontinuities (string defects) of finite length. Our main result is a compactness and $Γ$-convergence theorem which shows how the coarse grained limit energy depends on the geometry of the manifold in driving the…
Symmetry plays a basic role in variational problems (settled e.g. in $\mathbb R^{n}$ or in a more general manifold), for example to deal with the lack of compactness which naturally appear when the problem is invariant under the action of a noncompact group. In $\mathbb R^n$, a compactness result for invariant functions with respect to a subgroup $G$ of $\mathrm{O}(n)$ has been proved under the condition that the $G$ action on $\mathbb R^n$ is compatible, see \cite{willem}. As a first result we generalize this and show here that the compactness is recovered for particular subgroups of the isom…
In this paper, we establish gradient continuity for solutions to \[ (\partial_t - \operatorname{div}(A(x) \nabla u))^s =f,\ s \in (1/2, 1), \] when $f$ belongs to the scaling critical function space $L(\frac{n+2}{2s-1}, 1)$. Our main results Theorems 1.1 and 1.2 can be seen as a nonlocal generalization of a well-known result of Stein in the context of fractional heat type operators and sharpens some of the previous gradient continuity results which deals with $f$ in subcritical spaces. Our proof is based on an appropriate adaptation of compactness arguments, which has its roots in a fundamenta…
