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Local conditions on boundaries of $C^\infty$ Levi-flat hypersurfaces, in case the boundary is a generic submanifold, are studied. For nontrivial real analytic boundaries we get an extension and uniqueness result, which forces the…

Complex Variables · Mathematics 2008-06-08 Jiri Lebl

In this paper we consider germs of smooth Levi flat hypersurfaces, under the following notion of local equivalence: S_1 ~ S_2 if their one-sided neighborhoods admit a biholomorphism smooth up to the boundary. We introduce a simple invariant…

Complex Variables · Mathematics 2010-03-09 Giuseppe Della Sala

The first part of this paper considers higher order CR invariants of three dimensional hypersurfaces of finite type. Using a full normal form we give a complete characterization of hypersurfaces with trivial local automorphism group, and…

Complex Variables · Mathematics 2008-04-21 Martin Kolar

We establish an inequality among the Ricci curvature, the squared mean curvature, and the normal curvature for real hypersurfaces in complex space forms. We classify real hypersurfaces in two-dimensional non-flat complex space forms which…

Differential Geometry · Mathematics 2018-05-25 Toru Sasahara

First, we classify proper biharmonic Hopf real hypersurfaces in $\mathbb{C}P^2$. Next, we classify proper biharmonic real hypersurfaces with two distinct principal curvatures in $\mathbb{C}P^n$, where $n\geq 2$. Finally, we prove that…

Differential Geometry · Mathematics 2019-04-15 Toru Sasahara

We classify the homogeneous and isoparametric hypersurfaces of $\mathbb{S}^2\times\mathbb{S}^2$. In the classification, besides the hypersurfaces $\mathbb{S}^1(r)\times\mathbb{S}^2,\,r\in (0,1]$, it appears a family of hypersurfaces with…

Differential Geometry · Mathematics 2016-06-27 Francisco Urbano

Hypersurfaces are studied and classified under multiple additional assumptions in any Riemannian homogeneous space $(\mathbb{C}P^3, g_a)$, including nearly K\"ahler $\mathbb{C}P^3$. Notably, all extrinsically homogeneous hypersurfaces are…

Differential Geometry · Mathematics 2025-03-13 Michaël Liefsoens

We introduce new biholomorphic invariants for real-analytic hypersurfaces in 2-dimensional complex space and show how they can be used to show that a hypersurface possesses few automorphisms. We give conditions, in terms of the new…

Complex Variables · Mathematics 2007-05-23 P. Ebenfelt , B. Lamel , D. Zaitsev

Locally homogeneous strictly pseudoconvex hypersurfaces in $\mathbb C^2$ were classified by E.\,Cartan in 1932. In this work, we complete the classification of locally homogeneous strictly pseudoconvex hypersurfaces in $\mathbb C^3$.

Complex Variables · Mathematics 2019-06-28 Ilya Kossovskiy , Alexander Loboda

This article is dedicated to the centenary of the local CR equivalence problem, formulated by Henri Poincar\'{e} in 1907. The first part gives an account of Poincar\'{e}'s heuristic counting arguments, suggesting existence of infinitely…

Complex Variables · Mathematics 2007-05-23 Martin Kolar

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

We wish to attack the problems that H.~Anciaux and K.~Panagiotidou posed in [1], for non-degenerate real hypersurfaces in indefinite complex projective space. We will slightly change these authors' point of view, obtaining cleaner equations…

Differential Geometry · Mathematics 2019-02-18 Makoto Kimura , Miguel Ortega

We use the method of equivariant moving frames to revisit the problem of normal forms and equivalence of nondegenerate real hypersurfaces M \subset C^2 under the pseudo-group action of holomorphic transformations. The moving frame…

Differential Geometry · Mathematics 2022-02-28 Peter J. Olver , Masoud Sabzevari , Francis Valiquette

In our earlier work \cite{KZ}, we introduced an analytic regularizability theory for smooth strictly pseudoconvex hypersurfaces in complex space. That is, we found a necessary and sufficient condition for a hypersurface to be CR-equivalent…

Complex Variables · Mathematics 2025-06-26 Ilya Kossovskiy , Dmitri Zaitsev

We study the real analyticity of a CR mapping on the hypersurface $\h$ defined by $\h=\{z\in\C^n,\Re(z_n)+|z'|^2=0\}$ in model almost complex manifolds. We make use of a method of prolongation for the tangential Cauchy-Riemann equations and…

Complex Variables · Mathematics 2013-02-26 Marianne Peyron

In this paper, motivated by the work of Kim and Kolar for the case of pseudoconvex models which are sums of squares of polynomials, we study the Lie algebra of real-analytic infinitesimal $CR$ automorphisms of a model hypersurface $M_0$…

Complex Variables · Mathematics 2023-05-16 Cyril Julien , Francine Meylan

We investigate real hypersurfaces in complex space forms attaining equality in an inequality involving the contact $\delta$-invariant $\delta^c(2)$ introduced by Chen and Mihai in [3].

Differential Geometry · Mathematics 2020-03-06 Toru Sasahara

We answer two questions about the topology of end spaces of infinite type surfaces and the action of the mapping class group that have appeared in the literature. First, we give examples of infinite type surfaces with end spaces that are…

Geometric Topology · Mathematics 2022-03-16 Kathryn Mann , Kasra Rafi

We give a novel and effective criterion for algebraicity of rational normal analytic surfaces constructed from resolving the singularity of an irreducible curve-germ on $CP^2$ and contracting the strict transform of a given line and all but…

Algebraic Geometry · Mathematics 2012-11-20 Pinaki Mondal

In this paper, we show how to construct a special class of ruled hypersurfaces in the nonflat complex space forms $\mathbb{CP}^n$ and $\mathbb{C}H^n$. This is done by taking an arbitrary smooth curve in a totally geodesic (complex)…

Differential Geometry · Mathematics 2026-05-25 Thomas A. Ivey , Patrick J. Ryan