The Euler characteristic of hypersurfaces in space forms and applications to isoparametric hypersurfaces

Principal Curvatures of Isoparametric Hypersurfaces in Cp

Let M be an isoparametric hypersurface in CPn, and M the inverse image of M under the Hopf map. By using the relationship between the eigenvalues of the shape operators of M and M , we prove that M is homogeneous if and only if either g or l is constant, where g is the number of distinct principal curvatures of M and l is the number of non-horizontal eigenspaces of the shape operator on M .

Hypersurfaces of Constant Curvature in Space Forms

In this paper we shall discuss hypersurfaces M of space forms of constant curvature; where curvature means one of the symmetric functions of curvature associated to the second fundamental form. The values of the constant will be chosen so that the linearized equation will be an elliptic equation onM . For example, for surfaces in 3 the two possible curvatures are the mean curvature H and the Ga...

Euler Characteristic of Primitive T -hypersurfaces and Maximal Surfaces

Viro method plays an important role in the study of topology of real algebraic hypersurfaces. The T -primitive hypersurfaces we study here appear as the result of Viro’s combinatorial patchworking when one starts with a primitive triangulation. We show that the Euler characteristic of the real part of such a hypersurface of even dimension is equal to the signature of its complex part. We use th...

Rigidity Results for Hypersurfaces in Space Forms

Biharmonic Hypersurfaces in 4-dimensional Space Forms

We investigate proper biharmonic hypersurfaces with at most three distinct principal curvatures in space forms. We obtain the full classification of proper biharmonic hypersurfaces in 4-dimensional space forms.