x : Mn-1 ? Rn be an umbilical free hypersurface with non-zero principal curvatures. Then is associated a Laguerre metric g, tensor L, form C, and second fundamental B, which are invariants of under transformation group. In this paper, we will study the parallel nonnegative or non-positive tensor.

‎Based on a definition for circle in Finsler space‎, ‎recently proposed by one of the present authors and Z‎. ‎Shen‎, ‎a natural definition of extrinsic sphere in Finsler geometry is given and it is shown that a connected submanifold of a Finsler manifold is totally umbilical and has non-zero parallel mean curvature vector field‎, ‎if and only if its circles coincide with circles of the ambient...

A hypersurface is said to be totally biharmonic if all its geodesics are curves in the ambient space. We prove that a into space form an isoparametric hypersurface, which allows us give full classification of hypersurfaces these spaces. Moreover, restricting ourselves 3-dimensional case, we show surfaces Bianchi–Cartan–Vranceanu spaces and their classification. In particular, that, leaving asid...

In this paper we modify the maximum principal of (Galloway, 2000) for totally geodesic null hypersurfaces by proving a geometric maximum principle which obeys mean curvature inequalities of a family of totally umbilical null hypersurfaces of a spacetime manifold (Theorem 6). As a physical interpretation we show that, in particular, for a prescribed class of spacetimes the geometric inequality o...