A NOTE ON CONICAL KHLER-RICCI FLOW ON MINIMAL ELLIPTIC KHLER SURFACES

We prove that, under a semi-ampleness type assumption on the twisted canonical line bundle, the conical Kahler-Ricci flow on a minimal elliptic Kahler surface converges in the sense of currents to a generalized conical Kahler-Einstein on its canonical model. Moreover, the convergence takes place smoothly outside the singular fibers and the chosen divisor.

A Derivation of the Ricci Flow

In this work, we show that by restricting to the subgroup of time-independent coordinate transformations, then it is possible to derive the Ricci flow from the Bianchi identities. To achieve this, we first show that the field equations of the gravitational field, the Newton’s second law of classical dynamics, and the Maxwell field equations of the electromagnetic field all share the same mathematical structure. Consequently, the Ricci flow itself may be regarded as dynamical equations used to describe physical processes associated with the gravitational field, such as the process of smoothing out irregularities of distribution of matter in space.

Gradient estimates for porous medium equations under the Ricci flow

A local gradient estimate for positive solutions of porous medium equations on complete noncompact Riemannian manifolds under the Ricci flow is derived. Moreover, a global gradient estimate for such equations on compact Riemannian manifolds is also obtained.

Feature Preserving Parameterization for Quadrilateral Mesh Generation Based on Ricci Flow and Cross Field

We propose a newmethod to generate surface quadrilateralmesh by calculating a globally defined parameterization with feature constraints.In the field of quadrilateral generation with features,the cross field methods are wellknown because of their superior performance in feature preservation.The methods based on metrics are popular due to their sound theoretical basis,especially the Ricci flow algorithm.The cross field methods’major part,the Poisson equation,is challenging to solve in three dimensions directly.When it comes to cases with a large number of elements,the computational costs are expensive while the methods based on metrics are on the contrary.In addition,an appropriate initial value plays a positive role in the solution of the Poisson equation,and this initial value can be obtained from the Ricci flow algorithm.So we combine the methods based on metric with the cross field methods.We use the discrete dynamic Ricci flow algorithm to generate an initial value for the Poisson equation,which speeds up the solution of the equation and ensures the convergence of the computation.Numerical experiments show that our method is effective in generating a quadrilateral mesh for models with features,and the quality of the quadrilateral mesh is reliable.

Evolution of the First Eigenvalue of a (<i>p</i>,<i>q</i>)-Laplacian Under a Harmonic Ricci Flow

The properties of the first eigenvalue of a class of (p,q) Laplacian are investigated. A variational formulation for the first eigenvalue of the Laplacian on a closed Riemannian manifold is obtained. This eigenvalue corresponds to a nonlinear, coupled system of p-Laplacian partial differential equations. The main idea is to investigate the evolution of the first eigenvalue of the system under the Ricci harmonic flow. It is also possible to construct monotonic quantities based on them and study their evolution which is done.

A Mathematical Interpretation of Hawking’s Black Hole Theory by Ricci Flow

In this paper, using Perelman’s no local collapsing theorem and the geometric interpretation of Hamilton’s Harnack expressions along the Ricci flow introduced by R. Hamilton, we present a mathematical interpretation of Hawking’s black hole theory in [1].

W-entropy formulas on super Ricci flows and Langevin deformation on Wasserstein space over Riemannian manifolds Dedicated to Professor Zhiming Ma on His Seventieth Birthday

In this survey paper, we give an overview of our recent works on the study of the W-entropy for the heat equation associated with the Witten Laplacian on super-Ricci flows and the Langevin deformation on the Wasserstein space over Riemannian manifolds. Inspired by Perelman's seminal work on the entropy formula for the Ricci flow, we prove the W-entropy formula for the heat equation associated with the Witten Laplacian on n-dimensional complete Riemannian manifolds with the CD(K, m)-condition, and the W-entropy formula for the heat equation associated with the time-dependent Witten Laplacian on n-dimensional compact manifolds equipped with a(K, m)-super Ricci flow, where K ∈ R and m ∈ [n, ∞]. Furthermore, we prove an analogue of the W-entropy formula for the geodesic flow on the Wasserstein space over Riemannian manifolds.Our result improves an important result due to Lott and Villani(2009) on the displacement convexity of the Boltzmann-Shannon entropy on Riemannian manifolds with non-negative Ricci curvature. To better understand the similarity between above two W-entropy formulas, we introduce the Langevin deformation of geometric flows on the tangent bundle over the Wasserstein space and prove an extension of the W-entropy formula for the Langevin deformation. We also make a discussion on the W-entropy for the Ricci flow from the point of view of statistical mechanics and probability theory. Finally, to make this survey more helpful for the further development of the study of the W-entropy, we give a list of problems and comments on possible progresses for future study on the topic discussed in this survey.

Evolution and monotonicity of eigenvalues under the Ricci flow

Let （M,g（t）） be a compact Riemannian manifold and the metric g（t） evolve by the Ricci flow. We derive the evolution equation for the eigenvalues of geometric operator --△φ＋ cR under the Ricci flow and the normalized Ricci flow, where A, is the Witten-Laplacian operator, φ∈C∞（M）, and R is the scalar curvature with respect to the metric g（t）. As an application, we prove that the eigenvalues of the geometric operator are nondecreasing along the Ricci flow coupled to a heat equation for manifold M with some Ricci curvature 1 condition when c 〉1/4.

Relative volume comparison of Ricci flow

In this paper we derive a relative volume comparison of Ricci flow under a certain local curvature condition.It is a refinement of Perelman’s no local collapsing theorem in Perelman(2002).

Canonical solitons associated with generalized Ricci flows

We construct the canonical solitons,in terms of Cabezas-Rivas and Topping,associated with some generalized Ricci flows.

Estimates and Monotonicity of the First Eigenvalues Under the Ricci Flow on Closed Surfaces

In the paper we first derive theevolution equation for eigenvalues of geomet-ric operator-ΔФ+cR under the Ricci flow and the normalized Ricci flow on a closed Riemannian manifold M,where,is the Witten-Laplacian operator,Ф∈C^(∞)(M),and R is the scalar curvature.We then prove that the first eigenvalue of the geometricoperator is nondecreasing along the Ricci flow on closed surfaces with certain curva-ture conditions when 0<c≤1/2.As an application,we obtain some monotonicityformulae and estimates for the first eigenvalue on closed surfaces.

Survey on Discrete Surface Ricci Flow

Ricci flow deforms the Riemannian metric proportionally to the curvature, such that the curvature evolves according to a nonlinear heat diffusion process, and becomes constant eventually. Ricci flow is a powerful computational tool to design Riemannian metrics by prescribed curvatures This work surveys the theory of discrete surface Ricci flow registration and shape analysis. Surface Ricci flow has been generalized to the discrete setting. its computational algorithms, and the applications for surface

Local Aronson-Benilan Estimates for Porous Medium Equations under Ricci Flow

In this work we derive local gradient estimates of the Aronson-Benilan type for positive solutions of porous medium equations under Ricci flow with bounded Ricci curvature. As an application, we derive a Harnack type inequality.

First Eigenvalue Monotonicity for the p-Laplace Operator under the Ricci Flow

In this note, we discuss the monotonicity of the first eigenvalue of the p-Laplace operator （p ≥2） along the Ricci flow on closed Riemannian manifolds. We prove that the first eigenvalue of the p-Laplace operator is nondecreasing along the Ricci flow under some different curvature assumptions, and therefore extend some parts of Ma＇s results [Ann. Glob. Anal.Geom,29,287-292（2006）]

The Harnack Estimate for a Nonlinear Parabolic Equation under the Ricci Flow

Let （M,g（t））, 0 ≤ t ≤ T, be an n-dimensional closed manifold with nonnegative Ricci c for some constant C 〉 0 and g（t） evolving by the Ricci flow curvature, │Rc│ ≤C/t for some constant C 〉 0 and g（t） evolving by the Ricci flow gij/ t=-2Rij.In this paper, we derive a differential Harnack estimate for positive solutions to parabolic equations of the type u~ = /△u - aulogu - bu on M x （0,T], where a 〉 0 and b ∈ R.

The Logarithmic Sobolev Inequality Along the Ricci Flow:The Caseλ0(g0)=0

A uniform logarithmic Sobolev inequality,a uniform Sobolev inequality and a uniformκ-noncollapsing estimate along the Ricci flow are established in the situation that a certain smallest eigenvalue for the initial metric is zero.

The Logarithmic Sobolev and Sobolev Inequalities Along the Ricci Flow

Based on Perelman’s entropy monotonicity,uniform logarithmic Sobolev inequalities along the Ricci flow are derived.Then uniform Sobolev inequalities along theRicci floware derived via harmonic analysis of the integral transform of the relevant heat operator.These inequalities are fundamental analytic properties of the Ricci flow.They are also extended to the volume-normalized Ricci flow and the Kähler-Ricci flow.

The Chern-Ricci flow and holomorphic bisectional curvature

In this note, we show that on Hopf manifold S^(2n-1)×S^1, the non-negativity of the holomorphic bisectional curvature is not preserved along the Chern-Ricci flow.

Eigenvalues under the Backward Ricci Flow on Locally Homogeneous Closed 3-manifolds

In this paper, we study the evolving behaviors of the first eigenvalue of the Laplace- Beltrami operator under the normalized backward Ricci flow, construct various quantities which are monotonic under the backward Ricci flow and get upper and lower bounds. We prove that in cases where the backward Ricci flow converges to a sub-Riemannian geometry after a proper rescaling, the eigenvalue evolves toward zero.

Injectivity radius bound of Ricci flow with positive Ricci curvature and applications

We study the injectivity radius bound for 3-d Ricci flow with bounded curvature. As applications, we show the long time existence of the Ricci flow with positive Ricci curvature and with curvature decay condition at infinity. We partially settle a question of Chow-Lu-Ni [Hamilton＇s Ricci Flow, p. 302].