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We study regularity properties of CR maps in positive codimension valued in pseudoconvex manifolds which carry a nontrivial Levi foliation. We introduce an invariant which can be used to deduce that any sufficiently regular CR map from a…

Complex Variables · Mathematics 2023-02-28 Josef Greilhuber , Bernhard Lamel

We describe the structure of the singular sets of constant curvature, convex hypersurfaces in hyperbolic space for general convex curvature functions. We apply this result to the study of the ideal Plateau problem in hyperbolic space for…

Differential Geometry · Mathematics 2024-10-15 Graham Smith

The purpose of this article is to investigate the holomorphic vector fields tangent to a real hypersurface in $\mathbb C^2$ vanishing at an infinite type point.

Complex Variables · Mathematics 2014-08-19 Ninh Van Thu

We provide an explicit description of all rigid hypersurfaces that are equivalent to a Heisenberg sphere. These hypersurfaces are determined by 4 real parameters. The defining equations of the rigid spheres can also be viewed as the…

Complex Variables · Mathematics 2017-08-01 Vladimir Ezhov , Gerd Schmalz

We give local criteria for smooth non-embeddablity of Levi-flat manifolds. For this purpose, we pose an analogue of Ueda theory on the neighborhood structure of hypersurfaces in complex manifolds with topologically trivial normal bundles.

Complex Variables · Mathematics 2017-04-18 Takayuki Koike , Noboru Ogawa

In this paper, we discuss germs of smooth hypersurface in $\mathbb C^n$. We show that if a point on the boundary has infinite D'Angelo type, then there exists a formal complex curve in the hypersurface through that point.

Complex Variables · Mathematics 2009-11-13 John Erik Fornaess , Lina Lee , Yuan Zhang

In our earlier articles we studied tube hypersurfaces in ${\mathbb C}^3$ that are 2-nondegenerate and uniformly Levi degenerate of rank 1. In particular, we showed that the vanishing of the CR-curvature of such a hypersurface is equivalent…

Complex Variables · Mathematics 2018-09-24 Alexander Isaev

We prove a topological rigidity theorem for closed hypersurfaces of the Euclidean sphere and of an elliptic space form. It asserts that, under a lower bound hypothesis on the absolute value of the principal curvatures, the hypersurface is…

Differential Geometry · Mathematics 2018-09-28 Eduardo Longa , Jaime Ripoll

We construct a formal normal form for a real 2-codimensional submanifold $M\subset\mathbb{C}^{N+1}$ near a CR singularity approximating the sphere. This result gives a higher dimensional extension of Huang-Yin's normal form in…

Complex Variables · Mathematics 2017-09-19 Valentin Burcea

We study the principal curvatures of properly embedded constant mean curvature hypersurfaces in the Anti-de Sitter space $\mathbb{H}^{n,1}$. We generalize the notion of convex hull and give an upper bound on the principal curvatures which…

Differential Geometry · Mathematics 2025-08-08 Enrico Trebeschi

A result of Beauville states that with a few positive characterstic exceptions, the smooth hyperplane sections of hypersurfaces of degree $d>2$ in projective space are not all isomorphic. We address the question of whether these sections…

Algebraic Geometry · Mathematics 2007-05-23 Michael A. van Opstall , Razvan Veliche

We determine the second fundamental form of a variation of Hodge Structure of a smooth projective hypersurface using the classical identification of the Hodge structure and the action of the infinitesimal variation of Hodge structure with…

Algebraic Geometry · Mathematics 2020-07-14 Emmanuel Allaud

All hypersurface homogeneous locally rotationally symmetric spacetimes which admit conformal symmetries are determined and the symmetry vectors are given explicitly. It is shown that these spacetimes must be considered in two sets. One set…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Pantelis S. Apostolopoulos , Michael Tsamparlis

For a hypersurface in a projective space, we consider the set of pairs of a point and a line in the projective space such that the line intersects the hypersurface at the point with a fixed multiplicity. We prove that this set of pairs…

Algebraic Geometry · Mathematics 2010-12-13 Atsushi Ikeda

Basic aspects of the equiaffine geometry of level sets are developed systematically. As an application there are constructed families of $2n$-dimensional nondegenerate hypersurfaces ruled by $n$-planes, having equiaffine mean curvature…

Differential Geometry · Mathematics 2017-11-06 Daniel J. F. Fox

This paper is concerned with the completeness (with respect to the centroaffine metric) of hyperbolic centroaffine hypersurfaces which are closed in the ambient vector space. We show that completeness holds under generic regularity…

Differential Geometry · Mathematics 2016-06-17 Vicente Cortés , Marc Nardmann , Stefan Suhr

We prove that for every $n\geq 3$ the sharp upper bound for the dimension of the symmetry groups of homogeneous, 2-nondegenerate, $(2n+1)$-dimensional CR manifolds of hypersurface type with a $1$-dimensional Levi kernel is equal to $n^2+7$,…

Complex Variables · Mathematics 2022-03-01 David Sykes , Igor Zelenko

We discuss local polynomial convexity of real analytic Levi-flat hypersurfaces in $\mathbb C^n$, $n>1$, near singular points.

Complex Variables · Mathematics 2020-04-14 Rasul Shafikov , Alexandre Sukhov

We consider the problem $F=f(\nu)$ for strictly convex, closed hypersurfaces in hyperbolic space and solve it for curvature functions $F$ the inverses of which are of class $(K^*)$.

Differential Geometry · Mathematics 2007-05-23 Claus Gerhardt

We study the local equivalence problem for real-analytic ($\mathcal{C}^\omega$) hypersurfaces $M^5 \subset \mathbb{C}^3$ which, in coordinates $(z_1, z_2, w) \in \mathbb{C}^3$ with $w = u+i\, v$, are rigid: \[ u \,=\,…

Differential Geometry · Mathematics 2019-12-25 Wei Guo Foo , Joel Merker , The-Anh Ta