Characterizations of hypersurfaces with constant r-mean curvature
Embedded hypersurfaces; r-mean curvature; Compact hypersurfaces; Euclidean space; Open hemisphere; Hyperbolic space; Alexandrov theorem; Theorem of Montiel e Ros.
This thesis aims to present a proof of a theorem of Sebastián Montiel and Antonio Ros which characterizes the compact hypersurfaces, without boundary, with constant r-mean curvature embedded in the space forms. This theorem generalizes the classical theorem of Alexandrov and states that
"The only compact, without boundary, hypersurfaces with constant r-mean curvature for some r=1,...,n, embedded in the Euclidean space, in the open hemisphere of the Euclidean sphere, or in the hyperbolic space, are the geodesic hyperspheres."
We remark that, despite we follow the ideas of Montiel and Ros, we give a new approach for some steps of the proof presented here.