Let Mn be an n-dimensional compact minimal submanifolds in Sin（1）× R. We prove two pinching theorems by the Ricci curvature and the sectional curvature pinching conditions respectively. In fact, we characterize...Let Mn be an n-dimensional compact minimal submanifolds in Sin（1）× R. We prove two pinching theorems by the Ricci curvature and the sectional curvature pinching conditions respectively. In fact, we characterize the Clifford tori and Veronese submanifolds by our pinching conditions respectively.展开更多
A small cover is a closed manifold M^n with a locally standard （Z2）^n-action such that its orbit space is a simple convex polytope P^n. Let A^n denote an n-simplex and P（m） an m-gon. This paper gives formulas for ...A small cover is a closed manifold M^n with a locally standard （Z2）^n-action such that its orbit space is a simple convex polytope P^n. Let A^n denote an n-simplex and P（m） an m-gon. This paper gives formulas for calculating the number of D-J equivalent classes and equivariant homeomorphism classes of orientable small covers over the product space △^n1 × △^n2 × P（m）, where n1 is odd.展开更多
基金supported by National Natural Science Foundation of China (Grant No.11271214)
文摘Let Mn be an n-dimensional compact minimal submanifolds in Sin（1）× R. We prove two pinching theorems by the Ricci curvature and the sectional curvature pinching conditions respectively. In fact, we characterize the Clifford tori and Veronese submanifolds by our pinching conditions respectively.
基金supported by the National Natural Science Foundation of China(No.11371118)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20121303110004)the Natural Science Foundation of Hebei Province(No.A2011205075)
文摘A small cover is a closed manifold M^n with a locally standard （Z2）^n-action such that its orbit space is a simple convex polytope P^n. Let A^n denote an n-simplex and P（m） an m-gon. This paper gives formulas for calculating the number of D-J equivalent classes and equivariant homeomorphism classes of orientable small covers over the product space △^n1 × △^n2 × P（m）, where n1 is odd.
