仿射Kähler-Scalar曲率为零的紧致仿射Kähler流形

设x:M→A^(n+1)是由定义在凸域ΩA^n上的某局部严格凸函数x_(n+1)=f(x_1,...,x_n)给出的超曲面.考虑Hessian度量g=∑~2f /x_i_jdx_idx_j.若(M,g)是具有0仿射Khler-Scalar曲率的2维紧致Hessian流形,则函数f一定是二次多项式.

关于Bochner张量具有消灭条件的梯度收缩Kähler-Ricci孤立子

研究完备梯度收缩Kähler-Ricci孤立子,在Bochner张量的4阶散度等于零的条件下(即div^(4)(W)=▽_(k)▽_(j)▽_(i)▽_(l)W_(ijkl)=0),得到了其分类结果.

The Second Variation of the Functional L of Symplectic Critical Surfaces in Kähler Surfaces

Let M be a complete Kähler surface andbe a symplectic surface which is smoothly immersed in M.Letαbe the Kähler angle ofin M.In the previous paper Han and Li(JEMS 12:505–527,2010)2010,we study the symplectic critical surfaces,which are critical points of the functional L=1 cosαdμin the class of symplectic surfaces.In this paper,we calculate the second variation of the functional L and derive some consequences.In particular,we show that,if the scalar curvature of M is positive,is a stable symplectic critical surface with cosα≥δ>0,whose normal bundle admits a holomorphic section X∈L2(),thenis holomorphic.We construct symplectic critical surfaces in C2.We also prove a Liouville theorem for symplectic critical surfaces in C2.

Kähler Dark Matter, Dark Energy Cosmic Density and Their Coupling

We utilize homology and co-homology of a K3-Kähler manifold as a model for spacetime to derive the cosmic energy density of our universe and subdivide it into its three fundamental constituents, namely: 1) ordinary energy;2) pure dark energy and 3) dark matter. In addition, the fundamental coupling of dark matter to pure dark energy is analyzed in detail for the first time. Finally, the so-obtained results are shown to be in astounding agreement with all previous theoretical analysis as well as with actual accurate cosmic measurements.

Schwarz lemma from a Kähler manifold into a complex Finsler manifold

Suppose that M is a complete Kähler manifold such that its holomorphic sectional curvature is bounded from below by a constant and its radial sectional curvature is also bounded from below.Suppose that N is a strongly pseudoconvex complex Finsler manifold such that its holomorphic sectional curvature is bounded from above by a negative constant.In this paper,we establish a Schwarz lemma for holomorphic mappings f from M into N.As applications,we obtain a Liouville type rigidity result for holomorphic mappings f from M into N,as well as a rigidity theorem for bimeromorphic mappings from a compact complex manifold into a compact complex Finsler manifold.

L^(2) EXTENSIONS WITH SINGULAR METRICS ON K?HLER MANIFOLDS

In this paper,we give a survey of our recent results on extension theorems on Kähler manifolds for holomorphic sections or cohomology classes of(pluri)canonical line bundles twisted with holomorphic line bundles equipped with singular metrics,and also discuss their applications and the ideas contained in the proofs.

Remark on the Off-Diagonal Expansion of the Bergman Kernel on Compact Kähler Manifolds

In this short note,we compare our previous work on the off-diagonal expansion of the Bergman kernel and the preprint of Lu-Shiffman(arXiv:1301.2166).In particular,we note that the vanishing of the coefficient of p−1/2 is implicitly contained in Dai-Liu-Ma’s work(J.Differ.Geom.72(1),1-41,2006)and was explicitly stated in our book(Holomorphic Morse inequalities and Bergman kernels.Progress in Math.,vol.254,2007).

R^(5)中具有平行Fubini-Pick形式的Calabi超曲面的分类

Fubini-Pick形式关于Blaschke-Berwald度量(或中心仿射度量)平行的局部强凸等仿射(或中心仿射)超曲面分类问题,在过去十年内已被完全解决.文献[20]对Fubini-Pick形式关于Calabi度量平行的2,3维Calabi超曲面进行了分类,该文将其推广到4维的情形.

复Finsler流形上的Laplace算子及其应用

Laplace算子在微分几何的调和积分理论和Bochner技巧中起着重要的作用.研究Finsler流形上的调和积分理论和Bochner技巧的关键是定义一个适当的Laplace算子.目前,复Finsler流形上Laplace算子还没有统一的定义.本文简单综述了厦门大学多复变与复几何研究组在复Finsler流形上Laplace算子及其应用方面的研究成果.

Upper bound of Kahler angles on the β-symplectic critical surfaces

Let(M,g)be a Kähler surface andΣbe aβ-symplectic critical surface in M.If L_(q)(Σ)is bounded for some q>3,then we give a uniform upper bound for the Kähler angle onΣ.This bound only depends on M,q,βand the Lq functional ofΣ.For q>4,this estimate is known and we extend the scope of q.

非线性抛物方程的微分Harnack不等式

本文主要研究在Kähler-Ricci流和重整的Kähler-Ricci流演化下含位势的非线性抛物方程的微分Harnack不等式以及非线性倒向抛物方程的微分Harnack不等式.

Differential Correspondences and Control Theory

When a differential field K having n commuting derivations is given together with two finitely generated differential extensions L and M of K, an important problem in differential algebra is to exhibit a common differential extension N in order to define the new differential extensions L∩M and the smallest differential field (L,M ) ⊂ N containing both L and M. Such a result allows to generalize the use of complex numbers in classical algebra. Having now two finitely generated differential modules L and M over the non-commutative ring D = K [d1,...,dn] = K [d] of differential operators with coefficients in K, we may similarly look for a differential module N containing both L and M in order to define L∩M and L+M. This is exactly the situation met in linear or non-linear OD or PD control theory by selecting the inputs and the outputs among the control variables. However, in many recent books and papers, we have shown that controllability was a built-in property of a control system, not depending on the choice of inputs and outputs. The purpose of this paper is thus to revisit control theory by showing the specific importance of the two previous problems and the part plaid by N in both cases for the parametrization of the control system. An important tool will be the study of differential correspondences, a modern name for what was called Bäcklund problem during the last century, namely the elimination theory for groups of variables among systems of linear or nonlinear OD or PD equations. The main difficulty is to revisit differential homological algebra by using noncommutative localization as a way to generalize the symbolic calculus in the style of Heaviside and Mikusinski. Finally, when M is a D-module, this paper is using for the first time the fact that the system R = homK (M,K) is a D-module for the Spencer operator acting on sections, avoiding thus behaviours, trajectories and signal spaces in a purely formal way, contrary to a few recent works on this difficult subject.

Completing Einstein’s Spacetime

The four-dimensional character of Einstein’s spacetime is generally accepted in mainstream physics as beyond reasonable doubt correct. However the real problem is when we require scale invariance and that this spacetime be four-dimensional on all scales. It is true that on our classical scale, the 4D decouples into 3D plus one time dimension and that on very large scale only the curvature of spacetime becomes noticeable. However the critical problem is that such spacetime must remain 4D no matter how small the scale we are probing is. This is something of crucial importance for quantum physics. The present work addresses this basic, natural and logical requirement and shows how many contradictory results and shortcomings of relativity and quantum gravity could be eliminated when we “complete” Einstein’s spacetime in such a geometrical gauge invariant way. Concurrently the work serves also as a review of the vast Literature on E-Infinity theory used here.

利用磁性Jacobi场比较定理估计轨道球的体积

本文运用磁性Jacobi场与轨道球的体积公式的关系,估计轨道球的体积。主要利用磁性Jacobi场比较定理从上面来估计在Kähler磁场上轨道球的体积,其思想是将磁性Jacobi场放大,从而给出轨道球的体积。

Canonical Form Associated with an r-Jacobi Algebra

In this paper, we denote by A a commutative and unitary algebra over a commutative field K of characteristic 0 and r an integer ≥1. We define the notion of r-Jacobi algebra A and we construct the canonical form associated with the r-Jacobi algebra A.

六维近凯勒流形的Kodaira维数

本文主要研究了六维近凯勒流形的典范丛和Kodaira维数.证明了六维严格近凯勒流形的典范丛是拟全纯平凡的,从而其Kodaira维数为0.特别地,证明了三维复射影空间CP^3具有Kodaira维数不为-∞的近复结构.对于齐性的六维严格近凯勒流形,具体构造了它们典范丛的整体生成元.证明了齐性近凯勒流形F^3和CP^3的Hodge数h^1,0,h^2,0,h^2,3,h^1,3均为零.

Chern-Ricci curvatures, holomorphic sectional curvature and Hermitian metrics

We present some formulae related to the Chern-Ricci curvatures and scalar curvatures of special Hermitian metrics.We prove that a compact locally conformal Kähler manifold with the constant nonpositive holomorphic sectional curvature is K?hler.We also give examples of complete non-Kähler metrics with pointwise negative constant but not globally constant holomorphic sectional curvature,and complete non-Kähler metrics with zero holomorphic sectional curvature and nonvanishing curvature tensors.

关于复Monge-Ampère方程的一些研究

过去50年间,复Monge-Ampère方程是一个被广泛研究的主题,它在复分析、复几何和Kähler几何中有很多重要的应用.本文首先回顾一些经典结果,然后着重介绍关于复Monge-Ampère方程的Liouville定理、C^1,α估计和C^2,α估计,以及其在Sasakian几何中的一些应用.这些结果是与S.Dinew、管鹏飞、李超、李嘉禹和张享文等合作得到的.

关于6维近凯勒流形中二阶平行拉格朗日子流形的注记

证明6维严格近凯勒流形中的二阶平行拉格朗日子流形一定是全测地的,这推广了L.Vrancken等人文中的一个重要结果.特别地,得到了齐性近凯勒S^(3)×S^(3)中该类拉格朗日子流形的完全分类.