设 M 是单位球面 S^(n+1)中的一个闭极小浸入超曲面,h 是 M 的第二基本形式,s 是 h 的模长的平方。根据 Simons 已得到的结果,若在 M 上有0≤s≤n,则 s=0或 n。本文讨论如下问题:s 是否有另一个较大的值?若有,这个值是什么?此问题收集到...设 M 是单位球面 S^(n+1)中的一个闭极小浸入超曲面,h 是 M 的第二基本形式,s 是 h 的模长的平方。根据 Simons 已得到的结果,若在 M 上有0≤s≤n,则 s=0或 n。本文讨论如下问题:s 是否有另一个较大的值?若有,这个值是什么?此问题收集到[7],我们得到定理设 M 是 S^(n+1)中的闭定向极小浸入超曲面,若 s 为大于 n 的常数,则s>n+(5-17^(1/2))/(3+17^(1/2))n>n+(n/9)展开更多
We use a new method to construct a class of asymptotically locally flat, scalar flat metrics. These metrics were constructed via algebraic geometry method by LeBrun before and provide counterexamples to the generalize...We use a new method to construct a class of asymptotically locally flat, scalar flat metrics. These metrics were constructed via algebraic geometry method by LeBrun before and provide counterexamples to the generalized positive action conjecture of Hawking and Pope.展开更多
In this work, we study a class of special Finsler metrics F called arctangent Finsler metric, which is a special （α, β）-metric, where a is a Riemannian metric and β is a 1-form, We obtain a sufficient and necessa...In this work, we study a class of special Finsler metrics F called arctangent Finsler metric, which is a special （α, β）-metric, where a is a Riemannian metric and β is a 1-form, We obtain a sufficient and necessary condition that F is locally projectively fiat if and only if α and β satisfy two special equations. Furthermore we give the non-trivial solutions for F to be locally projectively fiat. Moreover, we prove that such projectively fiat Finsler metrics with constant flag curvature must be locally Minkowskian.展开更多
The analytical and numerical solutions of structure and curvature of two kinds of static spherically symmetric neutron stars are calculated. The results show that Ricci tensor and curvature scalar cannot denote the cu...The analytical and numerical solutions of structure and curvature of two kinds of static spherically symmetric neutron stars are calculated. The results show that Ricci tensor and curvature scalar cannot denote the curly character of the space directly, however, to static spherically symmetric stars, these two quantities can present the relative curly degree of the space and the matter distribution to a certain extent.展开更多
We obtain an inequality in Sm×R and Hm×R which is similar to DDVV conjecture.As an application,we show that a minimal submanifold in H m×R with nonnegative scalar curvature must be a surface of the type...We obtain an inequality in Sm×R and Hm×R which is similar to DDVV conjecture.As an application,we show that a minimal submanifold in H m×R with nonnegative scalar curvature must be a surface of the type γ×R,where γ is a geodesic in H m.In addition,we get a pinching theorem in Sm×R.展开更多
We study the ordinary differential equations related to rotationally symmetric pseudo-Khler metricsof constant scalar curvatures. We present various solutions on various holomorphic line bundles over projectivespaces ...We study the ordinary differential equations related to rotationally symmetric pseudo-Khler metricsof constant scalar curvatures. We present various solutions on various holomorphic line bundles over projectivespaces and their disc bundles, and discuss the phase change phenomenon when one suitably changes initialvalues.展开更多
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 nor...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.展开更多
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...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.展开更多
The Webster scalar curvature is computed for the sphere bundle T_1S of a Finsler surface(S, F) subject to the Chern-Hamilton notion of adapted metrics. As an application,it is derived that in this setting(T_1S, g Sasa...The Webster scalar curvature is computed for the sphere bundle T_1S of a Finsler surface(S, F) subject to the Chern-Hamilton notion of adapted metrics. As an application,it is derived that in this setting(T_1S, g Sasaki) is a Sasakian manifold homothetic with a generalized Berger sphere, and that a natural Cartan structure is arising from the horizontal 1-forms and the author associates a non-Einstein pseudo-Hermitian structure. Also, one studies when the Sasaki type metric of T_1S is generally adapted to the natural co-frame provided by the Finsler structure.展开更多
文摘设 M 是单位球面 S^(n+1)中的一个闭极小浸入超曲面,h 是 M 的第二基本形式,s 是 h 的模长的平方。根据 Simons 已得到的结果,若在 M 上有0≤s≤n,则 s=0或 n。本文讨论如下问题:s 是否有另一个较大的值?若有,这个值是什么?此问题收集到[7],我们得到定理设 M 是 S^(n+1)中的闭定向极小浸入超曲面,若 s 为大于 n 的常数,则s>n+(5-17^(1/2))/(3+17^(1/2))n>n+(n/9)
文摘We use a new method to construct a class of asymptotically locally flat, scalar flat metrics. These metrics were constructed via algebraic geometry method by LeBrun before and provide counterexamples to the generalized positive action conjecture of Hawking and Pope.
基金Project (No. 10571154) supported by the National Natural Science Foundation of China
文摘In this work, we study a class of special Finsler metrics F called arctangent Finsler metric, which is a special （α, β）-metric, where a is a Riemannian metric and β is a 1-form, We obtain a sufficient and necessary condition that F is locally projectively fiat if and only if α and β satisfy two special equations. Furthermore we give the non-trivial solutions for F to be locally projectively fiat. Moreover, we prove that such projectively fiat Finsler metrics with constant flag curvature must be locally Minkowskian.
基金The project supported by National Natural Science Foundation of China under Grant No. 10275099 and the China Postdoctoral Science Foundation under Grant No. 2005037175
文摘The analytical and numerical solutions of structure and curvature of two kinds of static spherically symmetric neutron stars are calculated. The results show that Ricci tensor and curvature scalar cannot denote the curly character of the space directly, however, to static spherically symmetric stars, these two quantities can present the relative curly degree of the space and the matter distribution to a certain extent.
基金supported by National Natural Science Foundation of China (Grant No.10871149)Research Fund for the Doctoral Program of Higher Education of China (Grant No. 200804860046)
文摘We obtain an inequality in Sm×R and Hm×R which is similar to DDVV conjecture.As an application,we show that a minimal submanifold in H m×R with nonnegative scalar curvature must be a surface of the type γ×R,where γ is a geodesic in H m.In addition,we get a pinching theorem in Sm×R.
基金supported by National Natural Science Foundation of China (Grant Nos.10425101, 10631050)National Basic Research Program of China (973 Project) (Grant No. 2006cB805905)
文摘We study the ordinary differential equations related to rotationally symmetric pseudo-Khler metricsof constant scalar curvatures. We present various solutions on various holomorphic line bundles over projectivespaces and their disc bundles, and discuss the phase change phenomenon when one suitably changes initialvalues.
基金supported by National Natural Science Foundation of China(Grant Nos.11401514,11371310,11101352 and 11471145)Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant Nos.13KJB110029 and 14KJB110027)+2 种基金Foundation of Yangzhou University(Grant Nos.2013CXJ001 and 2013CXJ006)Fund of Jiangsu University of Technology(Grant No.KYY13005)Qing Lan Project
文摘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.
基金the National Natural Science Foundation of China(No.10671214)the Science Foundation of Chongqing Education Committee(No.KJ080620)
文摘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.
文摘The Webster scalar curvature is computed for the sphere bundle T_1S of a Finsler surface(S, F) subject to the Chern-Hamilton notion of adapted metrics. As an application,it is derived that in this setting(T_1S, g Sasaki) is a Sasakian manifold homothetic with a generalized Berger sphere, and that a natural Cartan structure is arising from the horizontal 1-forms and the author associates a non-Einstein pseudo-Hermitian structure. Also, one studies when the Sasaki type metric of T_1S is generally adapted to the natural co-frame provided by the Finsler structure.
