Sharp estimates for mean curvature flow of graphs
Tobias H. Colding, W. P. Minicozzi
图的中曲率流的尖锐估计和例子来说明为什么这些是尖锐的。这些估计改进了Klaus Ecker和Gerhard Huisken的早期（非尖锐）估计。
Sharp estimates for mean curvature flow of graphs are shown and examples are given to illustrate why these are sharp. The estimates improves earlier (non-sharp) estimates of Klaus Ecker and Gerhard Huisken.
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Sharp lower bound on the curvatures of ASD connections over the cylinder
我们证明了一个尖锐的下界上的曲率非平坦ASD连接的圆柱。
Sharp Interior Gradient Estimate for Area Decreasing Graphical Mean Curvature Flow in Arbitrary Codimension
本文在任意余维情形下证明了面积递减图形式平均曲率流的锐利内部梯度估计，推广了已有结果。
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。
We prove that the boundary of a (not necessarily connected) bounded smooth set with constant nonlocal mean curvature is a sphere. More generally, and in contrast with what happens in the classical case, we show that the Lipschitz constant of the nonlocal mean curvature of such a boundary controls its $C^2$-distance from a single sphere. The corresponding stability inequality is obtained with a sharp decay rate.
Sharp trace theorems for null hypersurfaces on Einstein metrics with finite curvature flux
本文的主要目的是证明具有有限曲率通量的零超曲面上的尖迹和乘积估计的几何形式。这些估计对于控制零超曲面的几何形状起着至关重要的作用。该文件是基于经典的Littlewood -Paley理论的不变版本，在非交换设置，通过表面上的热流定义。
In this paper, we prove convergence of the high codimension mean curvature flow in the sphere to either a round point or a totally geodesic sphere assuming a pinching condition between the norm squared of the second fundamental form and the norm squared of the mean curvature and the background curvature of the sphere. We show that this pinching is sharp for dimension $n\geq 4$ but is not sharp for dimension $n=2,3$. For dimension $n=2$ and codimension $2$, we consider an alternative pinching condition which includes the normal curvature of the normal bundle. Finally, we sharpen the Chern-do Ca…
Sharp monotonicity for closed three-manifolds with positive scalar curvature
该研究针对具有正标量曲率的闭三维流形的自然格林函数，证明了两个严格单调性公式，并将其解释为格林函数下水平集的包围质量的单调性，推广了非负标量曲率情形的相关结果。
Sharp lower bound of the first eigenvalue of the $p$-Laplacian under integral Ricci curvature
该研究针对p≥2的闭流形，在小积分里奇曲率条件下，结合Sobolev截断的全局椭圆估计与一维比较剖面的严格扰动，证明了p-拉普拉斯算子第一非零特征值的尖锐Zhong-Yang型下界。
On simple geodesic disks of constant curvature, we derive new functional relations for the geodesic X-ray transform, involving a certain class of elliptic differential operators whose ellipticity degenerates normally at the boundary. We then use these relations to derive sharp mapping properties for the X-ray transform and its corresponding normal operator. Finally, we discuss the possibility of theoretically rigorous regularized inversions for the X-ray transform when defined on such manifolds.
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…
Sharp Quartic Pinching for the Mean Curvature Flow in the Sphere
本研究针对球面中平均曲率流，运用爆破论证等方法证明了精确四次曲率夹挤定理，推广了Pu的相关收敛性成果，无需Stampacchia迭代或积分分析即得到重标度的光滑收敛结果。
In this paper, based on the local comparison principle in [12], we study the local behavior of the difference of two spacelike graphs in a neighborhood of a second contact point. Then we apply it to the constant mean curvature equation in 3-dimensional Lorentz-Minkowski space $\mathbb{L}^3$ and get the uniqueness of critical point for the solution of such equation over convex domain, which is an analogue of the result in [28]. Last, by this uniqueness, we obtain a minimum principle for a functional depending on the solution and its gradient. This gives us a sharp gradient estimate for the solu…
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…
Sharp gradient estimates and monotonicity in positive Ricci curvature
本文在正 Ricci 曲率闭流形上证明了尖锐梯度估计，并将其与单调性公式联系起来，同时给出了 Bishop 定理的新证明。
It is well known that the Serrin condition is a necessary condition for the solvability of the Dirichlet problem for the prescribed mean curvature equation in bounded domains of $\mathbb{R}^n$ with certain regularity. In this paper we investigate the sharpness of the Serrin condition for the vertical mean curvature equation in the product $ M^n \times \mathbb{R} $. Precisely, given a $\mathscr{C}^2$ bounded domain $Ω$ in $M$ and a function $ H = H (x, z) $ continuous in $\overlineΩ\times\mathbb{R}$ and non-decreasing in the variable $z$, we prove that the strong Serrin condition $(n-1)\mathcal…
Rigidity and volume pinching for the sharp gradient estimate in positive Ricci curvature
该研究针对正里奇曲率流形，证明了其尖锐梯度估计的几乎刚性，建立梯度亏格与体积亏格的定量控制关系，还得到爱因斯坦流形的间隙定理及闭4维爱因斯坦流形的刚性定理。
Patch solutions for the surface quasigeostrophic (SQG) equation model sharp temperature fronts in atmospheric and oceanic flows. We establish local well-posedness for SQG sharp fronts of low Sobolev regularity, $H^{2+s}$ for arbitrarily small $s>0$, allowing for fronts with unbounded curvature.
Sharp Spectral Gap Estimates on Manifolds under Integral Ricci Curvature Bounds
本文在积分曲率边界下证明了紧流形上的尖锐谱间隙估计，推广了 Kröger (1992) 以及 Bakry 和 Qian (2000) 的结果，并证实了 Ramos 等人 (2020) 中的猜想。
Sharp Minkowski-Type Inequality in Cartan-Hadamard 3-Spaces
本文通过调和平均曲率流在Cartan-Hadamard 3空间中证明了锐利的Minkowski型不等式，改进了超曲面总平均曲率的已知估计，特别改进了Ghomi-Spruck的结果。
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
Two sharp comparison results are derived for three-dimensional complete noncompact manifolds with scalar curvature bounded from below. The first one concerns the Green's function. When the scalar curvature is nonnegative, it states that the rate of decay of an energy quantity over the level set is strictly less than that of the Euclidean space, unless the manifold itself is isometric to the Euclidean space. The result is in turn converted into a sharp area comparison for the level set of the Green's function when in addition the Ricci curvature of the manifold is assumed to be asymptotically n…
We consider the geodesic X-ray transform acting on solenoidal tensor fields on a compact simply connected manifold with strictly convex boundary and non-positive curvature. We establish a stability estimate of the form $L^2\mapsto H^{1/2}_{T}$, where the $H^{1/2}_{T}$-space is defined using the natural parametrization of geodesics as initial boundary points and incoming directions (fan-beam geometry); only tangential derivatives at the boundary are used. The proof is based on the Pestov identity with boundary term localized in frequency.
We present a rigidity scenario for complete Riemannian manifolds supporting the Heisenberg-Pauli-Weyl uncertainty principle with the sharp constant in $\mathbb R^n$ (shortly, sharp HPW principle). Our results deeply depend on the curvature of the Riemannian manifold which can be roughly formulated as follows: (a) When $(M,g)$ has non-positive sectional curvature, the sharp HPW principle holds on $(M,g)$. However, positive extremals exist in the sharp HPW principle if and only if $(M,g)$ is isometric to $\mathbb R^n$, $n={\rm dim}(M)$. (b) When $(M,g)$ has non-negative Ricci curvature, the shar…
A New Monotone Quantity in Mean Curvature Flow Implying Sharp Homotopic Criteria
本文在高余维图形平均曲率流中发现新单调量，利用面积递减条件证明其递增性，并据此得到复射影空间及球面相关映射的尖锐同伦判定准则。
The Extension for Mean Curvature Flow with Finite Integral Curvature in Riemannian Manifolds
研究了推广黎曼流形中中曲率流的积分条件。我们证明了在有限时间区间$[0,T)$上具有有限总中曲率的中曲率流解可以随时间$T$扩展.此外，我们还证明了该条件在某种意义上是最优的。
In this paper we consider complete noncompact Riemannian manifolds $(M, g)$ with nonnegative Ricci curvature and Euclidean volume growth, of dimension $n \geq 3$. We prove a sharp Willmore-type inequality for closed hypersurfaces $\partial Ω$ in $M$, with equality holding true if and only if $(M{\setminus}Ω, g)$ is isometric to a truncated cone over $\partialΩ$. An optimal version of Huisken's Isoperimetric Inequality for $3$-manifolds is obtained using this result. Finally, exploiting a natural extension of our techniques to the case of parabolic manifolds, we also deduce an enhanced version …
Entire scalar curvature flow and hypersurfaces of constant scalar curvature in Minkowski space
证明了Minkowski空间中无穷远点处具有给定类光方向集的具有常负数量曲率的整类空超曲面的存在性，构造了无穷远点处具有给定类光方向集的整类空数量曲率流，并证明了该流收敛于具有常数量曲率的类空超曲面.证明依赖于障碍的建设和先验估计。
Mean curvature flow without singularities
研究了定义在欧几里得空间子集上的完全解的图中曲率流。我们获得了长期的平稳存在。演化图的投影也解决了中曲率流。因此，这种方法允许通过研究具有一个额外维度的图形中曲率流来平滑地流过奇点。
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。
Curvature flows on four manifolds with boundary
给定一个具有光滑边界的紧致四维光滑黎曼流形$(M,g)$，考虑其内部具有$Q$ -曲率的发展方程，使其$T$ -曲率和平均曲率为零，并考虑其边界具有$T$ -曲率的发展方程，条件是$Q$ -曲率和中曲率为零.利用积分方法，在保形不变的假设下，证明了$Q$ -曲率流（或$T$ -曲率流）对给定$Q$ -曲率（或$T$ -曲率）的光滑度量的全局存在性和收敛性.
We provide explicit examples which show that mean convexity (i.e. positivity of the mean curvature) and positivity of the scalar curvature are non-preserved curvature conditions for hypersurfaces of the Euclidean space evolving under either the volume- or the area preserving mean curvature flow. The relevance of our examples is that they disprove some statements of the previous literature, overshadow a widespread folklore conjecture about the behaviour of these flows and bring out the discouraging news that a traditional singularity analysis is not possible for constrained versions of the mean…
It is well-known that the mean curvature flow is a formal gradient flow of the perimeter functional. However, by the work of Michor and Mumford [7,8], the formal Riemannian structure that is compatible with the gradient flow structure induces a degenerate metric on the space of hypersurfaces. It is then natural to ask whether there is a nondegenerate metric space of hypersurfaces, on which the mean curvature flow admits a gradient flow structure. In this paper we study the mean curvature flow on two nondegenerate metric spaces of simple closed plane curves: the uniformness-preserving metric st…
In [5], Sáez and Schnürer studied the graphical mean curvature flow of complete hypersurfaces defined on subsets of Euclidean space. They obtained long time existence. Moreover, they provided a new interpretation of weak mean curvature flow. In this paper, we generalize their results to a general curvature setting. Our key ingredient is the existence result of general curvature flow with boundary conditions, which is proved in Section 4.
Generalized existence of extremizers for the sharp $p$-Sobolev inequality on Riemannian manifolds with nonnegative curvature
研究非负曲率黎曼流形上sharp p-塞伯利格不等式极值函数的广义存在性，通过非光滑方法和Cheeger能量收敛性分析，揭示极值函数的全局行为。
Given a closed 3-manifold with an initial Riemannian metric of negative sec- tional curvature, we consider the cross curvature flow an evolution equation of metric on M3. We prove long-time existence of a solution to the cross curvature flow via the maximum principle theorem. Besides, we demonstrate the solution exists for all time and converges pointwisely to a hyperbolic metric
In this work, we propose a new evolving geometric flow (called translating mean curvature flow) for the translating solitons of hypersurfaces in $R^{n+1}$. We study the basic properties, such as positivity preserving property, of the translating mean curvature flow. The Dirichlet problem for the graphical translating mean curvature flow is studied and the global existence of the flow and the convergence property are also considered.
We prove some Liouville type theorems on smooth compact Riemannian manifolds with nonnegative sectional curvature and strictly convex boundary. This gives a nonlinear generalization in low dimension of the recent sharp lower bound of the first Steklov eigenvalue by Xia-Xiong and verifies partially a conjecture by the third author. As a consequence, we derive several sharp Sobolev trace inequalities on these manifolds.
Lagrangian mean curvature flow in Pseudo-Euclidean space
建立了伪欧几里得空间中与对数梯度流有关的整拉格朗日图的中曲率流的长期存在性和收敛性结果。
A sharp isoperimetric inequality and the top order $Q$-curvature
研究\(\mathbb{R}^n\)上特定度量的\(n\)阶\(Q\)曲率与截面曲率关系，基于此在\(Q_g^{(n)}\)非负时得到紧域\(\Omega\)的尖锐等周不等式，在\(Q_g^{(n)}\)非正且Cartan - Hadamard猜想成立时也得到相关尖锐不等式。
Properties of Translating Solutions to Mean Curvature Flow
本文研究了中曲率流和非线性流的中曲率幂变换解的凸性、内梯度估计、Liouville型定理和无穷远点的渐近性。
Bounded Ricci Curvature and Positive Scalar Curvature under Singular Ricci de Turck Flow
本文研究带孤立锥形奇点的空间上的Ricci de Turck流，证明其保持Ricci曲率初始正则性与附加假设下的数量曲率正性，为奇异Ricci流的曲率算子正性研究奠定基础。
Singular Perturbations of Mean Curvature Flow
本文通过高阶方程给出了欧几里得空间中任意余维子流形的中曲率流的一种正则化方法。我们证明了正则化问题在第一个奇异点之前的所有时刻都收敛于中曲率流。
A sharp Sobolev trace inequality involving the mean curvature on Riemannian manifolds
本文研究了具有边界$\pa M$的黎曼流形$(M,g)$上的尖锐Sobolev迹不等式$\|u\|_{L^{q}(\pa M)}^2\leq S \|\nabla_g u\|_{L^2(M)}^2 +A(M,g)\|u\|^2_{L^2(\pa M)}$的边界$L^2$项，其中$q=\frac{2(n-1)}{n-2}$，$S$是最佳常数，而$A(M,g)$是仅依赖于$M$和$g$的某个正常数.我们得到了一个涉及剩余项中的中曲率的尖锐迹不等式，一旦中曲率被任何更小的函数所取代，这个不等式通常会失效。
Mean curvature flow solitons from symmetry group viewpoint
确定了一般环境Riemannian流形中平均曲率流的对称群，基于此定义了广义孤立子，并给出非欧几里得曲面上的位似孤立子实例，证明所有仿射解均为自相似解。
The extension and convergence of mean curvature flow in higher codimension
本文首先研究了余维为$d\geq1$的黎曼流形中子流形的中曲率流的扩张的积分曲率条件，推广了Le-\cite{LS}和作者\cite{XYZ1,XYZ2}关于超曲面的中曲率流的扩张定理.利用扩张定理，证明了${R}^{n+d}$中闭子流形的中曲率流在适当的积分曲率条件下的两个收敛定理。
A convergence result of the Lagrangian mean curvature flow
证明了黎曼曲面间的辛同胚图的中曲率流在时间趋于无穷大时光滑收敛。
Sharp rigidity for quasilinear Liouville equation on manifolds with nonnegative Ricci curvature
研究具有非负Ricci曲率流形上的拟线性Liouville方程，通过解的最优对数下界得出流形与欧氏空间等距且解为标准泡解，证明中关键是对数下界与总体积上界联系，还提出并证明了关于解与几何相互作用的猜想。
Ancient mean curvature flows with finite total curvature
本文在具有有限全曲率和Morse指标$I$的极小超曲面上构造了$I$-族古代图形平均曲率流，并证明其具有有限全曲率和有限质量下降，其中一族为平均凸。
In [Vel94], Velazquez constructed a countable collection of mean curvature flow solutions in $\mathbb{R}^N$ in every dimension $N \ge 8$. Each of these solutions becomes singular in finite time at which time the second fundamental form blows up. In contrast, we confirm here that, in every dimension $N \ge 8$, a nontrivial subset of these solutions has uniformly bounded mean curvature.
We establish short-time existence of the smooth solution to the fractional mean curvature flow when the initial set is bounded and C^{1,1}-regular. We provide the same result also for the volume preserving fractional mean curvature flow.
We prove the existence of closed convex ancient solutions to curvature flows which become more and more oval for large negative times. The speed function is a general symmetric function of the principal curvatures, homogeneous of degree greater than one. This generalises previous work on the mean curvature flow and other one-homogeneous curvature flows. As an auxiliary result, we prove a new theorem on the convergence to a round point of convex rotationally symmetric hypersurfaces satisfying a suitable constraint on the curvatures.
Blow-up rate of the mean curvature during the mean curvature flow and a gap theorem for self-shrinkers
在本文中，我们证明了，中曲率爆破在第一奇异时间$T$的任何紧凑的，I型中曲率流的第第二基本型相同的速度。对于曲面的中曲率流，只要高斯密度小于2，我们也得到了类似的结果。我们的证明是基于连续重新标度和分类的自收缩。我们发现，所有的奇异集的概念定义在\cite{St}一致的任何I型中曲率流，从而推广了斯通的结果，建立了任何平均凸I型中曲率流。我们还建立了一个间隙定理的自收缩。
Blow-up of the mean curvature at the first singular time of the mean curvature flow
证明了欧几里得空间中的中曲率流在第一个奇异时刻发生中曲率爆破，至少在维数小于或等于7时是这样.我们证明了中曲率在中曲率流的奇点处爆炸，该流从无迹第二基本型的具有小L^2-范数的浸入闭超曲面开始（注意初始超曲面不一定是凸的）。作为这一结果证明的结果，我们还获得了球体沿着中曲率流相对于L^2范数的动力稳定性。
Mixed volume preserving curvature flows in hyperbolic space
考虑双曲空间中具有单调、对称、齐次一次曲率函数F的曲率流。此外，我们假设F是凹的和反凹的或凸的。对于紧致的初始超曲面，证明了其在球面上是严格凸的情形下，混合保体积曲率流的长时间存在性。此外，我们表明，这些流指数收敛在C-无穷拓扑的测地球。
Extend Mean Curvature Flow with Finite Integral Curvature
本文首先证明了有限时间区间$[0,T)$上的中曲率流的解在第二基本型范数的时空积分有限的条件下可以随时间$T$延拓.其次，证明了有限时间区间$[0,T)$上的确定平均曲率流的解可以随时间$T$延拓，只要中曲率的时空积分是有限的.此外，我们还表明这些条件在某种意义上是最优的。
Singularity Profile in the Mean Curvature Flow
本文研究了中曲率流的第一次奇点的几何性质。通过Huisken和Sinestrari的曲率捏挤估计，证明了欧几里得空间$\R^{n+1}$中具有正中曲率的超曲面的中曲率流是$κ$ -非坍缩的，并且爆破序列沿着子序列局部光滑地收敛到光滑的凸爆破解。作为结果，我们得到了平均凸流的一个局部Harnack不等式.
In this paper, we consider the problem of prescribing scalar curvature on n-sphere. Assume that the candidate curvature function $f$, which is allowed to change sign, satisfies some kind of Morse index or symmetry condition. By studying the well-known scalar curvature flow, we are able to prove that the flow converges to a metric with the prescribed function $f$ as its scalar curvature.
Singularity structure in mean curvature flow of mean convex sets
本文给出了三维平均凸集的中曲率流的一些结果。不严格地说，我们的结果证明了天真的图片中曲率流的唯一的奇异性是颈部捏，和组件的崩溃渐近圆球。
A note on sigular time of mean curvature flow
证明了完备黎曼流形中紧致子流形的中曲率流在无穷远时刻不可能形成奇点，如果周围的黎曼流形具有有界几何，并且满足一定的曲率和体积增长条件.
In this paper we analyze the behavior of the distance function under Ricci flows whose scalar curvature is uniformly bounded. We will show that on small time-intervals the distance function is $\frac12$-Hölder continuous in a uniform sense. This implies that the distance function can be extended continuously up to the singular time.
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