具有可反Douglas曲率的Matsumoto度量（英文）

本文得到Matsumoto度量具有可反Douglas曲率的充分必要条件,该条件蕴含存在具有可反Douglas曲率的非Douglas的Finsler度量.     

具有可反测地线的$(\alpha,\beta)$-度量

本文我们得到了$(\alpha,\beta)$-度量的测地系数$G^{i}(x,y)$和其逆$G^{i}(x,-y)$有相同Douglas曲率的充分必要条件.这个充分必要条件恰好是$(\alpha,\beta)$-度量具有可反测地线的充分必要条件.     

R^n空间上具有正曲率和负曲率的度量一些例子

From the class of conformally flat metric of gij=f(|x|^2)δij defined on R^n,where f:[0,∞]→（0,∞）is a C^2 function,we find one class of metrics with positive curvature and two classes of complete metrics with negative curvature.     

具有迷向S曲率Randers度量的几何意义

Riemann流形上的Zermelo航行为Randers度量提供了一个简洁而且清晰的几何背景．在这个背景下D．Bao，C．Robles和Z．Shen对于具有常旗曲率的Randers度量进行了完全分类．这篇论文中，我得到了判定具有特殊曲率性质的Randers度量的两个充分必要条件．从这两个条件出发，我得到了迷向S曲率的Randers度量的几何意义和一系列推论，并且构造了具有迷向S曲率Randers度量的新例子．最后，在Zermelo航行的背景下研究了Berwald型的Raiders度量．     

两类具有标量旗曲率的弱Berwald度量

In this paper, we study the （α,β）-metrics of scalar flag curvature in the form of F = α ＋ εβ ＋ κβ^2/α （ε and k ≠ 0 are constants） and F = α^2/α-β. We prove that these two kinds of metrics are weak Berwaldian if and only if they are Berwaldian and their flag curvatures vanish. In this case, the metrics are locally Minkowskian.     

一类具有标量旗曲率的Berwald(α,β)-度量(英文)

本文研究了一类具有F=α+εβ+kα²/β形式的Finsler度量,其中α=（aijyⁱy^j）^1/2是Riemann度量,β=b_iyⁱ是非零1-形式,ε和k≠0是常数。得到了这个Finsler度量的S曲率消失和成为弱Berwald度量的充要条件。另外通过证明发现具有标量期曲率的Finsler度量成为弱Berwald度量的充要条件是它们成为Berwald度量,并且期曲率消失。在这种情况下,该Finsler度量就是局部Minkowski度量。     

关于（α，β）-度量的S-曲率

给出（α，β）-度量F=αФ（α，β）的S-曲率的计算公式．证得对一般的（α，β）-度量，当β为关于α长度恒定的Killing1-形式时，S=0．研究了Matsumoto-度量F=α^2／（α-β）和（α，β），度量F=α＋εβ＋κ（β^2／α）的S-曲率，证得S=0当且仅当β为关于α长度恒定的Killing1-形式．同时还得到这两类度量成为弱Berwald度量的充要条件,其中Ф（s）为光滑函数，α（y）=√aij（x）y^iy^j为黎曼度量，β（y）=bi（x）y^i为非零1-形式且ε，κ≠0为常数．     

关于广义(α,β)-度量的若干Ricci曲率性质

本文研究了广义(α,β)-度量的Ricci曲率和Ricci曲率张量.首先,在一定条件下,本文给出了强Einstein广义(α,β)-度量的一个等价刻画.进一步,得到了广义(α,β)-度量是Ricci-齐次Finsler度量的一个充分必要条件.     

两类Cartan张量有界的(α,β)-度量（英文）

本文研究了两类重要的(α,β)-度量-(广义)Kropina度量和Matsumoto度量的Cartan张量.证明了这两类(α,β)-度量的Cartan张量是有界的,并由此给出了这两类度量的一些刚性结果及其应用.     

半对称度量循环联络的某些特征及曲率张量表示

The projective transformation of the special semi-symmetric metric recurrent connection is studied in this paper. First of all, an invariant under this transformation is granted; Secondly, by inducing of the invariant and making use of the properties that the corresponding covariant derivative keeps being fixed under the distinctness connection, the curvature tensor expression of the Riemannian manifold is posed at the same time.     

On Einstein Matsumoto metrics

Einstein metrics are solutions to Einstein field equation in General Relativity containing the Ricci-flat metrics. Einstein Finsler metrics which represent a non-Riemannian stage for the extensions of metric gravity, provide an interesting source of geometric issues and the (α,β)-metric is an important class of Finsler metrics appearing iteratively in physical studies. It is proved that every n-dimensional (n≥3) Einstein Matsumoto metric is a Ricci-flat metric with vanishing S-curvature. The main result can be regarded as a second Schur type Lemma for Matsumoto metrics.     

On spherically symmetric Finsler metrics with vanishing Douglas curvature

We obtain the differential equation that characterizes the spherically symmetric Finsler metrics with vanishing Douglas curvature. By solving this equation, we obtain all the spherically symmetric Douglas metrics. Many explicit examples are included.     

On Einstein Matsumoto metrics

We study a special class of Finsler metrics,namely,Matsumoto metrics F=α2α-β,whereαis a Riemannian metric andβis a 1-form on a manifold M.We prove that F is a(weak)Einstein metric if and only ifαis Ricci flat andβis a parallel 1-form with respect toα.In this case,F is Ricci flat and Berwaldian.As an application,we determine the local structure and prove the 3-dimensional rigidity theorem for a(weak)Einstein Matsumoto metric.     

Matsumoto Metrics of Constant Flag Curvature: A Puny Class of Finsler Metrics with Constant Curvature

The local structure of Finsler metrics of constant flag curvature have been historically mysterious. It is proved that every Matsumoto metric of constant flag curvature on a closed n-dimensional manifold of dimension n ≥ 3 is either Riemannian or locally Minkowskian.     

On Unitary Invariant Weakly Complex Berwald Metrics with Vanishing Holomorphic Curvature and Closed Geodesics

In this paper, the authors construct a class of unitary invariant strongly pseudoconvex complex Finsler metrics which are of the form F =√[ rf(s- t)[, where r = ||v||~ 2, s =| z,v |~2/r, t =|| z||~ 2, f(w) is a real-valued smooth positive function of w ∈ R,and z is in a unitary invariant domain M  C~n. Complex Finsler metrics of this form are unitary invariant. We prove that F is a class of weakly complex Berwald metrics whose holomorphic curvature and Ricci scalar curvature vanish identically and are independent of the choice of the function f. Under initial value conditions on f and its derivative f, we prove that all the real geodesics of F =√[rf(s- t)] on every Euclidean sphere S~(2n-1) M are great circles.     

Best Sobolev Constants and Manifolds with Positive Scalar Curvature Metrics

We study the Yamabe invariant of manifolds which admit metrics of positive scalar curvature. Analysing `best Sobolev constants'we give a technique to find positive lower bounds for the invariant.We apply these ideas to show that for any compact Riemannian manifold (N ⁿ ,g) of positive scalarcurvature there is a positive constant K =K(N, g), which depends only on (N, g), such that for any compact manifold M ^m , the Yamabe invariantof M ^m × N ⁿ is no less than K times the invariant ofS ^{n + m} . We will find some estimates for the constant K in the case N =S ⁿ .