Lévy噪声驱动的随机微分方程的分部积分公式与应用

本文使用Malliavin分析与有限跳逼近方法,对于一类由从属Brown运动驱动的随机微分方程的半群建立Driver型分部积分公式.作为该公式的应用,本文得到半群的推移Harnack不等式以及热核估计.主要结果应用于由α稳定型过程驱动的随机微分方程.     

Ricci流与超Ricci流上的Li-Yau-Hamilton Harnack不等式 献给余家荣教授100华诞

本文对赋予依赖时间变化的加权紧致与完备Riemann流形上的时变Witten Laplace算子的热方程的正解证明Li-Yau-Hamilton型微分Harnack不等式和Harnack不等式.特别地,本文对赋予Ricci流或倒向Ricci流的紧致与完备Riemann流形上的Laplace-Beltrami算子的热方程的正解证明Li-Yau-Hamilton型微分Harnack不等式和Harnack不等式.     

带有不同权函数的退化拟线性椭圆方程弱解的Holder正则性

我们研究了一类系数依赖于两不同权函数的退化拟线性椭圆方程．利用加权Sobolev不等式,加权Poincare不等式及Moser迭代技巧,得到了非负弱解的Harnack不等式,证明了弱解的H61der连续性．     

带有不同权函数的退化拟线性椭圆方程弱解的Hlder正则性

我们研究了一类系数依赖于两不同权函数的退化拟线性椭圆方程.利用加权Sobolev不等式,加权Poincar'e不等式及Moser迭代技巧,得到了非负弱解的Harnack不等式,证明了弱解的Ho¨lder连续性.     

紧Riemann流形的高阶特征值估计

对Ricci曲率具负下界的紧Riemann流形,本文获得了热方程正解优化的梯度估计及Harnack不等式,证明了高阶特征值下界定量估计的猜想．     

微积分、Malliavin分析与变测度耦合

从微积分中的分部积分公式出发,引入Malliavin分析和变测度耦合方法,并简要介绍它们在随机微分方程研究中的应用,包括建立Bismut公式、Driver公式、Harnack不等式以及推移Harnack不等式.     

Khler-Ricci流下带有位能的热方程的微分Harnack不等式

主要研究了在Khler-Ricci流下的Khler流形上具有位能热方程的微分Harnack不等式,并利用它们得到了对应的W泛函和F泛函的单调性.     

一类具有交叉扩散的捕食模型非常数正解的存在性

研究了一类具有扩散和交叉扩散项的Holling-Tanner捕食-食饵模型.首先利用最大值原理和Harnack不等式给出正解的先验估计,进一步利用度理论得到非常数正解的存在性与不存在性,从而给出非常数正解存在的充分条件.     

一类多维非线性渗流方程解的有限传播性质

本文讨论具有强非线性源与对流项的渗流方程,利用其解的Harnack不等式得到弱解的具有限传播速度的性质或正解分界面的存在性与增长性.     

一类具不同权函数的线性退化椭圆方程弱解的Hlder连续性

本文研究了如下退化椭圆方程-∑ni,j=1Di(aij(x)Dju+diu)+∑ni=1biDiu+eu=f-∑ni=1Difi在具不同权函数下弱解的正则性.在方程低阶项系数属于退化Morrey空间的假定下,利用加权Sobolev不等式,退化Morrey空间的加权嵌入引理和经典的Mose迭代方法,证明了方程的弱解是局部有界的,获得了非负弱解的Harnack不等式,得到了方程弱解的Hlder连续性.     

New Differential Harnack Inequalities for Nonlinear Heat Equations

This paper deals with constrained trace, matrix and constrained matrix Harnack inequalities for the nonlinear heat equation ωt = ?ω + aωln ω on closed manifolds. A new interpolated Harnack inequality for ωt = ?ω-ωln ω +εRω on closed surfaces under ε-Ricci flow is also derived. Finally, the author proves a new differential Harnack inequality for ωt= ?ω-ωln ω under Ricci flow without any curvature condition. Among these Harnack inequalities, the correction terms are all time-exponential functions, which are superior to time-polynomial functions.     

黎曼流形上薛定谔方程的Harnack估计

推导了薛定谔方程正解的一种新的整体梯度估计和Harnack不等式,推广了一些有关热方程的结论,并且得到了一个关于薛定谔算子的刘维尔定理.     

Interpolating Between Li-Yau's and Hamilton's Harnack Inequalities on a Surface

We establish a one-parameter family of Harnack inequalities connecting Li and Yau's differential Harnack inequality for the heat equation to Hamilton's Harnack inequality for the Ricci flow on a 2-dimensional manifold with positive scalar curvature.     

Remarks on differential Harnack inequalities

In this paper, we give a generalization of (global and local) differential Harnack inequalities for heat equations obtained by Li and Xu [J.F. Li, X.J. Xu, Differential Harnack inequalities on Riemannian manifolds I: linear heat equation, Adv. Math. 226 (5) (2011) 4456–4491] and Baudoin and Garofalo [F. Baudoin, N. Garofalo, Perelman’s entropy and doubling property on Riemannian manifolds, J. Geom. Anal. 21 (2011) 1119–1131]. From this we can derive new Harnack inequalities and new lower bounds for the associated heat kernel. Also we provide some new entropy formulas with monotonicity.     

Dimension-Independent Harnack Inequalities for Subordinated Semigroups

Dimension-independent Harnack inequalities are derived for a class of subordinate semigroups. In particular, for a diffusion satisfying the Bakry-Emery curvature condition, the subordinate semigroup with power α satisfies a dimension-free Harnack inequality provided \(\alpha \in \left(\frac{1}{2},1 \right)\), and it satisfies the log-Harnack inequality for all α?∈?(0, 1). Some infinite-dimensional examples are also presented.     

Differential Harnack estimates for backward heat equations with potentials under the Ricci flow

In this paper, we derive a general evolution formula for possible Harnack quantities. As a consequence, we prove several differential Harnack inequalities for positive solutions of backward heat-type equations with potentials (including the conjugate heat equation) under the Ricci flow. We shall also derive Perelman's Harnack inequality for the fundamental solution of the conjugate heat equation under the Ricci flow.     

Interpolating between constrained Li–Yau and Chow–Hamilton Harnack inequalities on a surface

We establish a one-parameter family of Harnack inequalities connecting the constrained trace Li–Yau differential Harnack inequality for the heat equation to the constrained trace Chow–Hamilton Harnack inequality for the Ricci flow on a 2-dimensional closed manifold with positive scalar curvature, and thereby generalize Chow’s interpolated Harnack inequality (J. Partial Diff. Eqs. 11 (1998), 137–140).     

Interpolating between constrained Li–Yau and Chow–Hamilton Harnack inequalities for a nonlinear parabolic equation

We establish a one-parameter family of Harnack inequalities connecting the constrained trace Li–Yau differential Harnack inequality for a nonlinear parabolic equation to the constrained trace Chow–Hamilton Harnack inequality for this nonlinear equation with respect to evolving metrics related to the Ricci flow on a 2-dimensional closed manifold. This result can be regarded as a nonlinear version of the previous work of Y. Zheng and the author [J.-Y. Wu, Y. Zheng, Interpolating between constrained Li–Yau and Chow–Hamilton Harnack inequalities on a surface, Arch. Math., 94 (2010) 591–600].     

Reflecting Diffusion Processes on Manifolds Carrying Geometric Flow

Let \(L_t:=\Delta _t+Z_t\) for a \(C^{\infty }\)-vector field Z on a differentiable manifold M with boundary \(\partial M\), where \(\Delta _t\) is the Laplacian operator, induced by a time dependent metric \(g_t\) differentiable in \(t\in [0,T_\mathrm {c})\). We first establish the derivative formula for the associated reflecting diffusion semigroup generated by \(L_t\). Then, by using parallel displacement and reflection, we construct the couplings for the reflecting \(L_t\)-diffusion processes, which are applied to gradient estimates and Harnack inequalities of the associated heat semigroup. Finally, as applications of the derivative formula, we present a number of equivalent inequalities for a new curvature lower bound and the convexity of the boundary. These inequalities include the gradient estimates, Harnack inequalities, transportation-cost inequalities and other functional inequalities for diffusion semigroups.