The logarithmic Sobolev inequality along the Ricci flow in dimension 2

具有渐近非负Bakry-Émery Ricci曲率的流形上的Sobolev不等式

Sobolev Inequality on Manifolds With Asymptotically Nonnegative Bakry-Émery Ricci Curvature

本文受已有工作启发，在具有密度且Bakry-Émery Ricci曲率渐近非负的流形上证明了Sobolev不等式。

Entropy Functionals, Sobolev Inequalities and kappa-Noncollapsing Estimates along the Ricci Flow

In this survey we review Hamilton's entropy and Perelman's entropy, and provide motivations for these concepts. Then we review recent results on the logarithmic Sobolev inequality, the Sobolev inequalities and kappa-noncollapsing estimates along the Ricci flow, including the Ricci flow with surgeries.

A uniform Sobolev inequality for ancient Ricci flows with bounded Nash entropy

This note is a continuation of [CMZ21]. We shall show that an ancient Ricci flow with uniformly bounded Nash entropy must also have uniformly bounded $ν$-functional. Consequently, on such an ancient solution there are uniform logarithmic Sobolev and Sobolev inequalities. We emphasize that the main theorem in this paper is true so long as the theory in [Bam20c] is valid, and in particular, when the underlying manifold is closed.

A local Sobolev inequality on Ricci flow and its applications

In this article, we prove a local Sobolev inequality for complete Ricci flows. Our main result is that the local $ν$-functional of a disk on a Ricci flow depends only on the Nash entropy based at the center of the disk, and consequently depends only on the volume of the disk. Furthermore, we introduce some applications of this local Sobolev inequality. These applications reveal the way in which the local geometry evolves along Ricci flow. In particular, we show that several classical theorems related to Perelman's monotonicity formula can be derived from our results.

A uniform Sobolev inequality under Ricci flow

Let ${\bf M}$ be a compact Riemannian manifold and the metrics $g=g(t)$ evolve by the Ricci flow. We prove the following result. The Sobolev imbedding by Aubin or Hebey, perturbed by a scalar curvature term and modulo sharpness of constants, holds uniformly for $({\bf M}, g(t))$ for all time if the Ricci flow exists for all time; and if the Ricci flow develops a singularity in finite time, then the same Sobolev imbedding holds uniformly after a standard normalization. As a consequence, long time non-collapsing results are derived, which improve Perelman's local non-collapsing results. An appli…

具有渐近非负中间里奇曲率的流形中子流形的对数-Sobolev不等式

The Log-Sobolev inequality for a submanifold in manifolds with asymptotic non-negative intermediate Ricci curvature

本文在具有渐近非负中间里奇曲率和欧氏体积增长的完备非紧黎曼流形上，证明了子流形的尖锐对数-Sobolev不等式，推广了Dong-Lin-Lu等人的已有结果。

Gradient estimates for weighted $p$-Laplacian equations on Riemannian manifolds with a Sobolev inequality and integral Ricci bounds

In this paper, we consider the non-linear general $p$-Laplacian equation $Δ_{p,f}u+F(u)=0$ for a smooth function $F$ on smooth metric measure spaces. Assume that a Sobolev inequality holds true on $M$ and an integral Ricci curvature is small, we first prove a local gradient estimate for the equation. Then, as its applications, we prove several Liouville type results on manifolds with lower bounds of Ricci curvature. We also derive new local gradient estimates provided that the integral Ricci curvature is small enough.

The logarithmic Sobolev inequality along the Ricci flow

We derive a logarithmic Sobolev inequality along the Ricci flow without any restriction on time, which depends only on the initial metric via rudimentary geometric data, assuming only that a certain first eigenvalue is positive. As a consequence we obtain a uniform Sobolev inequality along the Ricci flow without any restriction on time. One application of it is a uniform kappa-noncollapsing estimate which holds true for all time. We also obtain similar results for bounded time without assuming the eigenvalue condition. The results extend to the Ricci flow with surgeries.

Uniform Sobolev inequalities for manifolds evolving by Ricci flow

Let M be a compact n-dimensional manifold, $n\ge 2$, with metric g(t) evolving by the Ricci flow $\partial g_{ij}/\partial t=-2R_{ij}$ in (0,T) for some $T\in\Bbb{R}^+\cup\{\infty\}$ with $g(0)=g_0$. Let $λ_0(g_0)$ be the first eigenvalue of the operator $-Δ_{g_0} +\frac{R(g_0)}{4}$ with respect to g_0. We extend a recent result of R. Ye and prove uniform logarithmic Sobolev inequality and uniform Sobolev inequalities along the Ricci flow for any $n\ge 2$ when either $T<\infty$ or $λ_0(g_0)>0$. As a consequence we extend Perelman's local $κ$-noncollapsing result along the Ricci flow for any $n…

具有非负中间Ricci曲率的流形中的Sobolev不等式

Sobolev inequalities in manifolds with nonnegative intermediate Ricci curvature

本文利用Alexandrov-Bakelman-Pucci方法，将Michael-Simon型Sobolev不等式推广到具有非负中间Ricci曲率的Riemannian流形中的子流形上，并由此导出极小子流形的等周不等式。

The (logarithmic) Sobolev inequalities along geometric flow and applications

For some class of geometric flows, we obtain the (logarithmic) Sobolev inequalities and their equivalence up to different factors directly and also obtain the long time non-collapsing and non-inflated properties, which generalize the results in the case of Ricci flow or List-Ricci flow or harmonic-Ricci flow. As applications, for mean curvature flow in Lorentzian space with nonnegative sectional curvature and twisted Kähler-Ricci flow on Fano manifolds, we get the results above.

Time-dependent Sobolev inequality along the Ricci flow

In this article we get a time-dependent Sobolev inequality along the Ricci flow which generalizes the earlier results of Zhang, Ye, Hsu. As an application of the time-dependent Sobolev inequality, we also get a growth of the ratio of bob-collapsing along the Ricci flow.

非紧致黎曼流形上具有下界曲率的Sobolev和Moser-Trudinger不等式

Sharp Sobolev and Moser-Trudinger inequalities on noncompact Riemannian manifolds with Ricci curvature bounded below

本文研究了非紧致黎曼流形上具有下界曲率的Sobolev和Moser-Trudinger不等式，得出了最佳常数。

Inégalité de Sobolev et volume asymptotique

A result of M. Ledoux is that a complete Riemannian manifold with non negative Ricci curvature satisfying the Euclidean Sobolev inequality is the Euclidean space. We present a shortcut of the proof. We also give a refinement of a result of B-L. Chen et X-P. Zhu about locally conformally flat manifolds with non negative Ricci curvature. Eventually, we discuss Ledoux's result when the hypothesis on the Ricci curvature is weakened on a hypothesis on the scalar curvature.

Strong non-collapsing and uniform Sobolev inequalities for Ricci flow with surgeries

We prove a uniform Sobolev inequality for Ricci flow, which is independent of the number of surgeries. As an application, under less assumptions, a non-collapsing result stronger than Perelman's $κ$ non-collapsing with surgery is derived. The proof is shorter and seems more accessible. The result also improves some earlier ones where the Sobolev inequality depended on the number of surgeries.

Heat kernel on Ricci shrinkers

In this paper, we systematically study the heat kernel of the Ricci flows induced by Ricci shrinkers. We develop several estimates which are much sharper than their counterparts in general closed Ricci flows. Many classical results, including the optimal Logarithmic Sobolev constant estimate, the Sobolev constant estimate, the no-local-collapsing theorem, the pseudo-locality theorem and the strong maximum principle for curvature tensors, are essentially improved for Ricci flows induced by Ricci shrinkers. Our results provide many necessary tools to analyze short time singularities of the Ricci…

An upper bound of the heat kernel along the harmonic-Ricci flow

In this paper, we first derive a Sobolev inequality along the harmonic-Ricci flow. We then prove a linear parabolic estimate based on the Sobolev inequality and Moser's iteration. As an application, we will obtain an upper bound estimate for the heat kernel under the flow.

具有常长度平均曲率向量的闭子流形的对数Sobolev不等式

A logarithmic Sobolev inequality for closed submanifolds with constant length of mean curvature vector

该研究在微分几何领域证明了非负截面曲率流形中具常长度平均曲率向量的闭子流形满足对数Sobolev不等式，丰富了子流形几何的分析工具。

具有中间Ricci曲率下界的流形中Michael-Simon-Sobolev不等式的最优输运方法

Optimal Transport Approach to Michael-Simon-Sobolev Inequalities in Manifolds with Intermediate Ricci Curvature Lower Bounds

该研究将最优输运的McCann定理推广至子流形场景，证明了满足中间Ricci曲率下界条件的流形内子流形的Michael-Simon-Sobolev不等式，涵盖了已有相关研究结论的变体情形。

New logarithmic Sobolev inequalities and an ε-regularity theorem for the Ricci flow

In this note we prove a new ε-regularity theorem for the Ricci flow. Let (M^n,g(t)) with t\in [-T,0] be a Ricci flow and H_{x} the conjugate heat kernel centered at a point (x,0) in the final time slice. Substituting H_{x} into Perelman's W-functional produces a monotone function W_{x}(s) of s \in [-T,0], the pointed entropy, with W_{x}(s) <= 0, and W_{x}(s) = 0 iff (M,g(t)) is isometric to the trivial flow on R^n. Our main theorem asserts the following: There exists an ε>0, depending only on T and on lower scalar curvature and μ-entropy bounds for (M,g(-T)), such that W_{x_0}(s) > -εimplies |…

The logarithmic Sobolev inequality for a submanifold in manifold with nonnegative sectional curvature

We prove a sharp logarithmic Sobolev inequality which holds for compact submanifolds without boundary in Riemannian manifold with nonnegative sectional curvature of arbitrary dimension and codimension, while the ambient manifold needs to have a specific Euclid-like property. Like the Michael-Simon Sobolev inequality, this inequality includes a term involving the mean curvature. This extends a recent result of S. Brendle with Euclidean setting.

Ancient Ricci flows with asymptotic solitons

We study ancient Ricci flows which admit asymptotic solitons in the sense of Perelman. We prove that the asymptotic solitons must coincide with Bamler's tangent flows at infinity. Furthermore, we show that Perelman's $ν$-functional is uniformly bounded on such ancient solutions; this fact leads to logarithmic Sobolev inequalities and Sobolev inequalities. Lastly, as an important tool for the proofs of the above results, we also show that, for a complete Ricci flow with bounded curvature, the bound of the Nash entropy depends only on the local geometry around an $H_n$-center of its base point.

Sharp Morrey-Sobolev inequalities and eigenvalue problems on Riemannian-Finsler manifolds with nonnegative Ricci curvature

Combining the sharp isoperimetric inequality established by Z. Balogh and A. Kristály [Math. Ann., in press, doi:10.1007/s00208-022-02380-1] with an anisotropic symmetrization argument, we establish sharp Morrey-Sobolev inequalities on $n$-dimensional Finsler manifolds having nonnegative $n$-Ricci curvature. A byproduct of this method is a Hardy-Sobolev-type inequality in the same geometric setting. As applications, by using variational arguments, we guarantee the existence/multiplicity of solutions for certain eigenvalue problems and elliptic PDEs involving the Finsler-Laplace operator. Our r…

Extremals of Log Sobolev inequality on non-compact manifolds and Ricci soliton structures

In this paper we establish the existence of extremals for the Log Sobolev functional on complete non-compact manifolds with Ricci curvature bounded from below and strictly positive injectivity radius, under a condition near infinity. When Ricci curvature is also bounded from above we get exponential decay at infinity of the extremals. As a consequence of these analytical results we establish, under the same assumptions, that non-trivial shrinking Ricci solitons support a gradient Ricci soliton structure. On the way, we prove two results of independent interest: the existence of a distance-like…

具有Ricci下界的黎曼流形上Sobolev不等式稳定性综述

An overview of the stability of Sobolev inequalities on Riemannian manifolds with Ricci lower bounds

本文综述了具有Ricci曲率下界的黎曼流形上Sobolev不等式稳定性的最新进展，重点介绍了光滑与非光滑几何方法的结合，并针对非负Ricci曲率和欧氏体积增长情形给出了自包含的稳定性证明概述，最后讨论了相关结果和开放问题。

具有Ricci曲率下界的黎曼流形上Sobolev不等式的稳定性

Stability of Sobolev inequalities on Riemannian manifolds with Ricci curvature lower bounds

该文研究带Ricci曲率下界的黎曼流形上两类Sobolev不等式的定性稳定性，证明正曲率下几乎极值函数逼近球面极值函数、非负曲率欧氏增长情形下逼近欧氏极值函数，还推出Yamabe度量稳定性结果，方法基于广义集中紧性与奇异空间刚性结论。

非紧致黎曼流形上带有有界瑞奇曲率的尖锐Sobolev不等式

Sharp Sobolev inequalities on noncompact Riemannian manifolds with bounded Ricci curvature

研究非紧致黎曼流形上带有有界瑞奇曲率的尖锐Sobolev不等式，通过等周轮廓的渐进行展和局部Sobolev不等式推导

Quantitative Sobolev extensions and the Neumann heat kernel for integral Ricci curvature conditions

We prove the existence of Sobolev extension operators for certain uniform classes of domains in a Riemannian manifold with an explicit uniform bound on the norm depending only on the geometry near their boundaries. We use this quantitative estimate to obtain uniform Neumann heat kernel upper bounds and gradient estimates for positive solutions of the Neumann heat equation assuming integral Ricci curvature conditions and geometric conditions on the boundary. Those estimates also imply quantitative lower bounds on the first Neumann eigenvalue of the considered domains.

Sharp isoperimetric and Sobolev inequalities in spaces with nonnegative Ricci curvature

By using optimal mass transport theory we prove a sharp isoperimetric inequality in ${\sf CD} (0,N)$ metric measure spaces assuming an asymptotic volume growth at infinity. Our result extends recently proven isoperimetric inequalities for normed spaces and Riemannian manifolds to a nonsmooth framework. In the case of $n$-dimensional Riemannian manifolds with nonnegative Ricci curvature, we outline an alternative proof of the rigidity result of S. Brendle (2021). As applications of the isoperimetric inequality, we establish Sobolev and Rayleigh-Faber-Krahn inequalities with explicit sharp const…

古老Ricci流的一个刚性结果

A rigidity result for ancient Ricci flows

该研究仅借助无穷附近尖锐对数Sobolev泛函的大小条件，证明了曲率无符号约束的古老Ricci流的刚性结果，且该结果和II型古老Ricci流及其反向极限的识别问题相关。

Sobolev inequalities in manifolds with nonnegative curvature

We prove a sharp Sobolev inequality on manifolds with nonnegative Ricci curvature. Moreover, we prove a Michael-Simon inequality for submanifolds in manifolds with nonnegative sectional curvature. Both inequalities depend on the asymptotic volume ratio of the ambient manifold.

The logarithmic Sobolev inequality for a submanifold in Euclidean space

We prove a sharp logarithmic Sobolev inequality which holds for submanifolds in Euclidean space of arbitrary dimension and codimension. Like the Michael-Simon Sobolev inequality, this inequality includes a term involving the mean curvature.

The Log Entropy Functional Along the Ricci Flow

In this paper we introduce the log entropy functional and establish its monotonicity along the Ricci flow. One consequence of it is the monotonicity of the logarithmic Sobolev constant along the Ricci flow.

Smoothing metrics on closed Riemannian manifolds through the Ricci flow

Under the assumption of the uniform local Sobolev inequality, it is proved that Riemannian metrics with an absolute Ricci curvature bound and a small Riemannian curvature integral bound can be smoothed to having a sectional curvature bound. This partly extends previous a priori estimates of Ye Li (J. Geom. Anal. 17 (2007) 495-511; Advances in Mathematics 223 (2010) 1924-1957).

A simple proof on the non-existence of shrinking breathers for the Ricci flow

Suppose $M$ is a compact n-dimensional manifold, $n\ge 2$, with a metric $g_{ij}(x,t)$ that evolves by the Ricci flow $\partial_tg_{ij}=-2R_{ij}$ in $M\times (0,T)$. We will give a simple proof of a recent result of Perelman on the non-existence of shrinking breather without using the logarithmic Sobolev inequality.

Sharp logarithmic Sobolev inequalities on gradient solitons and applications

We show that gradient shrinking, expanding or steady Ricci solitons have potentials leading to suitable reference probability measures on the manifold. For shrinking solitons, as well as expanding soltions with nonnegative Ricci curvature, these reference measures satisfy sharp logarithmic Sobolev inequalities with lower bounds characterized by the geometry of the manifold. The geometric invariant appearing in the sharp lower bound is shown to be nonnegative. We also characterize the expanders when such invariant is zero. In the proof various useful volume growth estimates are also established…

Sharp decay estimates for the logarithmic fast diffusion equation and the Ricci flow on surfaces

We prove the sharp local L^1 - L^\infty smoothing estimate for the logarithmic fast diffusion equation, or equivalently, for the Ricci flow on surfaces. Our estimate almost instantly implies an improvement of the known L^p - L^\infty estimate for p larger than 1. It also has several applications in geometry, providing the missing step in order to pose the Ricci flow with rough initial data in the noncompact case, for example starting with a general noncompact Alexandrov surface, and giving the sharp asymptotics for the contracting cusp Ricci flow, as we show elsewhere.

在非负曲率流形上通过ABP方法建立对数Sobolev不等式

Logarithmic Sobolev inequality in manifolds with nonnegative curvature via the ABP method

本文通过ABP方法，在非负曲率流形上建立了最优的对数Sobolev不等式，并揭示了最优常数与渐近体积比的关系。

Bochner formulas, functional inequalities and generalized Ricci flow

As a consequence of the Bochner formula for the Bismut connection acting on gradients, we show sharp universal Poincaré and log-Sobolev inequalities along solutions to generalized Ricci flow. Using the two-form potential we define a twisted connection on spacetime which determines an adapted Brownian motion on the frame bundle, yielding an adapted Malliavin gradient on path space. We show a Bochner formula for this operator, leading to characterizations of generalized Ricci flow in terms of universal Poincaré and log-Sobolev type inequalities for the associated Malliavin gradient and Ornstein-…

几何不等式与梯度收缩 Ricci 孤立子的刚性

Geometric inequalities and rigidity of gradient shrinking Ricci solitons

该研究证明完备梯度收缩 Ricci 孤立子上六类几何不等式与热核估计等价存在，并给出紧致情形下的积分间隙刚性结果。

Logarithmic Sobolev inequality for diffusion semigroups

Through the main example of the Ornstein-Uhlenbeck semigroup, the Bakry-Emery criterion is presented as a main tool to get functional inequalities as Poincaré or logarithmic Sobolev inequalities. Moreover an alternative method using the optimal mass transportation, is also given to obtain the logarithmic Sobolev inequality.

On logarithmic Sobolev inequalities for the heat kernel on the Heisenberg group

In this note, we derive a new logarithmic Sobolev inequality for the heat kernel on the Heisenberg group. The proof is inspired from the historical method of Leonard Gross with the Central Limit Theorem for a random walk. Here the non commutative nature of the increments produces a new gradient which naturally involves a Brownian bridge on the Heisenberg group. This new inequality contains the optimal logarithmic Sobolev inequality for the Gaussian distribution in two dimensions. We compare this new inequality with the sub-elliptic logarithmic Sobolev inequality of Hong-Quan Li and with the mo…

Logarithmic Hardy-Littlewood-Sobolev Inequality on Pseudo-Einstein 3-manifolds and the Logarithmic Robin Mass

Given a three dimensional pseudo-Einstein CR manifold $(M,T^{1,0}M,θ)$, we study the existence of a contact structure conformal to $θ$ for which the logarithmic Hardy-Littlewood-Sobolev (LHLS) inequality holds. Our approach closely follows \cite{Ok1} in the Riemannian setting. For this purpose, we introduce the notion of Robin mass as the constant term appearing in the expansion of the Green's function of the $P'$-operator. We show that the LHLS inequality appears when we study the variation of the total mass under conformal change. Then we exhibit an Aubin type result guaranteeing the existen…

在无限维约化海森堡群上的对数Sobolev不等式

Logarithmic Sobolev inequalities on infinite-dimensional reduced Heisenberg groups

本文在无限维约化海森堡群上构造了热核测度，并研究了其中的亚椭圆对数Sobolev不等式。

非紧自收缩子上的对数 Sobolev 不等式

The Logarithmic Sobolev inequality on non-compact self-shrinkers

本文利用 ABP 方法将 Brendle 关于闭自收缩子的最优对数 Sobolev 不等式推广到欧氏空间中完备、非紧、适当嵌入的自收缩子，得到 Ecker 结果的尖锐版本。

Rigidity and almost rigidity of Sobolev inequalities on compact spaces with lower Ricci curvature bounds

We prove that if $M$ is a closed $n$-dimensional Riemannian manifold, $n \ge 3$, with ${\rm Ric}\ge n-1$ and for which the optimal constant in the critical Sobolev inequality equals the one of the $n$-dimensional sphere $\mathbb{S}^n$, then $M$ is isometric to $\mathbb{S}^n$. An almost-rigidity result is also established, saying that if equality is almost achieved, then $M$ is close in the measure Gromov-Hausdorff sense to a spherical suspension. These statements are obtained in the ${\rm RCD}$-setting of (possibly non-smooth) metric measure spaces satisfying synthetic lower Ricci curvature bo…

A Gaussian upper bound of the conjugate heat equation along an extended Ricci flow

In this paper, we derive a Sobolev inequality along an extended Ricci flow and prove a point-wise Guassian type bound for the fundamental solutions of the conjugate heat equation under the flow.

General Sobolev Inequality on Riemannian Manifold

Let M be a complete n-dimensional Riemannian manifold, if the sobolev inqualities hold on M, then the geodesic ball has maximal volume growth; if the Ricci curvature of M is nonnegative, and one of the general Sobolev inequalities holds on M, then M is diffeomorphic to $R^{n}$.

Sobolev, Poincare and isoperimetric inequalities for subelliptic diffusion operators satisfying a generalized curvature dimension inequality

By adapting some ideas of M. Ledoux \cite{ledoux2}, \cite{ledoux-stflour} and \cite{Led} to a sub-Riemannian framework we study Sobolev, Poincaré and isoperimetric inequalities associated to subelliptic diffusion operators that satisfy the generalized curvature dimension inequality that was introduced by F. Baudoin and N. Garofalo in \cite{Bau2}. Our results apply in particular on all CR Sasakian manifolds whose horizontal Webster-Tanaka-Ricci curvature is non negative, all Carnot groups with step two, and wide subclasses of principal bundles over Riemannian manifolds whose Ricci curvature is …

球面上的共形对数拉普拉斯算子：Yamabe型问题与Sobolev空间

The conformal logarithmic Laplacian on the sphere: Yamabe-type problems and Sobolev spaces

该论文研究球面上的共形对数拉普拉斯算子，建立其与ℝ^N中对数拉普拉斯算子的联系，引入对应希尔伯特空间，衔接Yamabe型问题分类结果并推广至弱情形。

对数 Sobolev 不等式中的等号情形

Equality in the logarithmic Sobolev inequality

本文研究正 $\mathrm{Ric}_{\infty}$ 加权 Riemann 流形上对数 Sobolev 不等式的等号刚性，借助 Klartag 的针状分解证明等号时必分裂出一维 Gaussian 空间，并给出相关开放问题。

Ollivier曲率、等周、集中不等式与Log-Sobolev不等式

Ollivier curvature, Isoperimetry, concentration, and Log-Sobolev inequalitiy

本文引入马尔可夫链上程函方程的拉普拉斯分离原理，证明了非负Ollivier曲率下的等周集中不等式，并解决了多个关于修正log-Sobolev不等式的开放问题。

具有非负 Ricci 曲率的流形上的 Hardy 型不等式

Hardy type inequalities on manifolds with nonnegative Ricci curvature

本文研究非负 Ricci 曲率且具欧氏体积增长的高维流形，证明了三类 Hardy 型不等式。

对双曲空间和黎曼流形上的对数Sobolev、泊松和Beckner不等式的研究

Logarithmic Sobolev, Poincaré and Beckner Inequalities on Hyperbolic Spaces and Riemannian Manifolds

本文研究了双曲空间和黎曼流形上的对数Sobolev、泊松和Beckner不等式，通过改进的Pólya-Szegö不等式和半群方法，揭示了这些不等式对几何和等周性质的依赖性。