TAIWANESE JOURNAL OF MATHEMATICS
|
2016年
/
20卷
/
05期
关键词:
Riemannian and Lorentzian manifolds;
Spacelike and timelike submanifolds;
Umbilic point;
Submanifold totally geodesic at a point;
Mean curvature vector field;
Sphere;
Hyperbolic space;
CONSTANT MEAN-CURVATURE;
SPACELIKE HYPERSURFACES;
SITTER SPACE;
CIRCLES;
D O I:
10.11650/tjm.20.2016.7383
中图分类号:
O1 [数学];
学科分类号:
0701 ;
070101 ;
摘要:
Several characterizations of umbilic points of submanifolds in arbitrary Riemannian and Lorentzian manifolds are given. As a consequence, we obtain new characterizations of spheres in the Euclidean space and of hyperbolic spaces in the Lorentz-Minkowski space. We also prove the Lorentzian version of a classical result by Cartan.