Li-Yau Harnack Estimates for a Heat-Type Equation Under the Geometric Flow

in Potential Analysis (2018)

Local curvature estimates for the Ricci-harmonic flow

in Math ArXiv (2018)

In this paper we give an explicit bound of Δ_g(t)u(t)and the local curvature estimates for the Ricci-harmonic flow under the condition that the Ricci curvature is bounded along the flow. In the second ... [more ▼]

In this paper we give an explicit bound of Δ_g(t)u(t)and the local curvature estimates for the Ricci-harmonic flow under the condition that the Ricci curvature is bounded along the flow. In the second part these local curvature estimates are extended to a class of generalized Ricci flow, introduced by the author \cite{LY1}, whose stable points give Ricci-flat metrics on a complete manifold, and which is very close to the (K,N)-super Ricci flow recently defined by Xiangdong Li and Songzi Li \cite{LL2014}. Next we propose a conjecture for Einstein's scalar field equations motivated by a result in the first part and the bounded L^2-curvature conjecture recently solved by Klainerman, Rodnianski and Szeftel \cite{KRS2015}. In the last two parts of this paper, we discuss two notions of "Riemann curvature tensor" in the sense of Wylie-Yeroshkin \cite{KW2017, KWY2017, Wylie2015, WY2016}, respectively, and Li \cite{LY3}, whose "Ricci curvature" both give the standard Bakey-\'Emery Ricci curvature \cite{BE1985}, and the forward and backward uniqueness for the Ricci-harmonic flow. [less ▲]

Long time existence and bounded scalar curvature in the Ricci-harmonic flow

in Journal of Differential Equations (2018), 265(1), 69-97

In this paper we study the long time existence of the Ricci-harmonic flow in terms of scalar curvature and Weyl tensor which extends Cao's result \cite{Cao2011} in the Ricci flow. In dimension four, we ... [more ▼]

In this paper we study the long time existence of the Ricci-harmonic flow in terms of scalar curvature and Weyl tensor which extends Cao's result \cite{Cao2011} in the Ricci flow. In dimension four, we also study the integral bound of the ``Riemann curvature'' for the Ricci-harmonic flow generalizing a recently result of Simon \cite{Simon2015}. [less ▲]

Harnack estimates for nonlinear parabolic equations under the Ricci flow

E-print/Working paper (2017)

In this paper, we consider first the Li-Yau Harnack estimates for a nonlinear parabolic equation $\partial_{t}u=\Delta_{t}u-qu -au(\ln u)^{\alpha}$ under the Ricci flow, where $\alpha>0$ is a constant. To ... [more ▼]

In this paper, we consider first the Li-Yau Harnack estimates for a nonlinear parabolic equation $\partial_{t}u=\Delta_{t}u-qu -au(\ln u)^{\alpha}$ under the Ricci flow, where $\alpha>0$ is a constant. To extend these estimates to a more general situation, in the second part, we consider the gradient estimates for a positive solution of the nonlinear parabolic equation $\partial _{t}u=\Delta _{t}u+hu^{p}$ on a Riemannian manifold whose metrics evolve under the geometric flow $\partial _{t}g(t)=-2S_{g(t)}$. To obtain these estimates, we introduce a quantity $\underline{\boldsymbol{S}}$ along the flow which measures whether the tensor $S_{ij}$ satisfies the second contracted Bianchi identity. Under conditions on ${\rm Ric}_{g(t)}, S_{g(t)}$, and $\underline{\boldsymbol{S}}$, we obtain the gradient estimates. [less ▲]

Harnack estimates for a heat-type equation under the Ricci flow

in Journal of Differential Equations (2016), 260(4), 3270-3301

In this paper, we consider the gradient estimates for a positive solution of the nonlinear parabolic equation ∂tu=Δtu+hup∂tu=Δtu+hup on a Riemannian manifold whose metrics evolve under the Ricci flow. Two ... [more ▼]

In this paper, we consider the gradient estimates for a positive solution of the nonlinear parabolic equation ∂tu=Δtu+hup∂tu=Δtu+hup on a Riemannian manifold whose metrics evolve under the Ricci flow. Two Harnack inequalities and other interesting results are obtained. [less ▲]

Li-Yau-Hamilton estimates and Bakry-Emery-Ricci curvature

in Nonlinear Analysis: Theory, Methods and Applications (2015), 113

In this paper we derive Cheng–Yau, Li–Yau, Hamilton estimates for Riemannian manifolds with Bakry–Emery–Ricci curvature bounded from below, and also global and local upper bounds, in terms of ... [more ▼]

In this paper we derive Cheng–Yau, Li–Yau, Hamilton estimates for Riemannian manifolds with Bakry–Emery–Ricci curvature bounded from below, and also global and local upper bounds, in terms of Bakry–Emery–Ricci curvature, for the Hessian of positive and bounded solutions of the weighted heat equation on a closed Riemannian manifold. [less ▲]

Mabuchi and Aubin-Yau functionals over complex surfaces

in Journal of Mathematical Analysis and Applications (2014), 416(1), 81-98

Li-Yau estimates for a nonlinear parabolic equation on manifolds

in Mathematical Physics, Analysis and Geometry (2014)

On an extension of the H^k n curvature flow

in Science China Mathematics (2012), 55(1), 99-118

Harnack inequality for the negative power Gaussian curvature flow

in Proceedings of the American Mathematical Society (2011), 139(10), 3070-3717