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We classify locally defined non-spherical real-analytic hypersurfaces in complex space whose Levi form has no more than one negative eigenvalue and for which the dimension of the group of local CR-automorphisms has the second largest value.

Complex Variables · Mathematics 2007-05-23 Vladimir Ezhov , Alexander Isaev

We show that for a real-analytic connected holomorphically nondegenerate 5-dimensional CR-hypersurface $M$ and its symmetry algebra $\mathfrak{s}$ one has either: (i) $\dim\mathfrak{s}=15$ and $M$ is spherical (with Levi form of signature…

Complex Variables · Mathematics 2017-10-17 Alexander Isaev , Boris Kruglikov

Real-analytic CR functions on real-analytic CR singular submanifolds are not in general restrictions of holomorphic functions, unlike in the CR nonsingular case. We give a simple condition that completely characterizes those quadric CR…

Complex Variables · Mathematics 2024-05-24 Jiri Lebl , Alan Noell , Sivaguru Ravisankar

It is shown that a formal mapping between two real-analytic hypersurfaces in complex space is convergent provided that neither hypersurface contains a nontrivial holomorphic variety. For higher codimensional generic submanifolds,…

Complex Variables · Mathematics 2007-05-23 M. S. Baouendi , P. Ebenfelt , L. P. Rothschild

Using the theory of exterior differential systems, we study the existence of germ of pseudo-holomorphic disk in a real analytic hypersurface locally defined in a complex manifold equipped with J a real analytic almost complex structure. The…

Complex Variables · Mathematics 2025-01-09 Pierre Bonneau , Emmanuel Mazzilli

A primary goal in this paper is to study the question that asks when a real analytic submanifold $M$ in ${\mathbb{C}}^{n+1}$ bounds a real analytic (up to $M$) Levi-flat hypersurface $\hat{M}$ near $p\in M$ such that $\hat{M}$ is foliated…

Complex Variables · Mathematics 2012-10-19 Xiaojun Huang , Wanke Yin

We study the holomorphic extendability of smooth CR maps between real analytic strictly pseudoconvex hypersurfaces in complex affine spaces of different dimensions.

Complex Variables · Mathematics 2007-05-23 Sergey Pinchuk , Alexandre Sukhov

Here, we resume and broaden the results concerned which appeared in math.AG/0101098 and math.AG/0104021. We start from summing up our example of a complex algebraic surface which is not deformation equivalent to its complex conjugate and…

Algebraic Geometry · Mathematics 2007-05-23 V. Kharlamov , Vik. Kulikov

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

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 study non-degenerate CR geometries of hypersurface type that are symmetric in the sense that, at each point, there is a CR transformation reversing the CR distribution at that point. We show that such geometries are either flat or…

Complex Variables · Mathematics 2018-08-10 Jan Gregorovič , Lenka Zalabová

Let $M$ be a real-analytic connected CR-hypersurface of CR-dimension $n>0$ having a point of Levi-nondegeneracy. The following alternative is demonstrated for both the symmetry algebra $s$ and the automorphism group $G$ of $M$. Denote by…

Complex Variables · Mathematics 2019-12-09 Boris Kruglikov

We study the equivalence problem under projective transformation for CR-hypersurfaces of complex projective space. A complete set of projective differential invariants for analytic hypersurfaces is given. The self-dual strongly C-linearly…

Differential Geometry · Mathematics 2010-10-28 C. Hammond , C. Robles

We study CR hypersurfaces in $\mathbb{C}^4$ that are Levi degenerate with constant rank Levi form, and moreover finitely nondegenerate. Each of these can be described as a deformation of a model CR hypersurface by adding terms of higher…

Complex Variables · Mathematics 2025-04-08 Jan Gregorovič , David Sykes

We study singular real analytic Levi-flat subsets invariant by singular holomorphic foliations in complex projective spaces. We give sufficient conditions for a real analytic Levi-flat subset to be the pull-back of a semianalytic Levi-flat…

Complex Variables · Mathematics 2021-07-06 Andrés Beltrán , Arturo Fernández-Pérez , Hernán Neciosup

We prove several new transversality results for formal CR maps between formal real hypersurfaces in complex space. Both cases of finite and infinite type hypersurfaces are tackled in this note.

Complex Variables · Mathematics 2015-06-26 Bernhard Lamel , Nordine Mir

We study the non-embddability property for a class of real hypersurfaces, called real hypersurfaces of involution type, into the sphere in the low codimensional case, by making use of property of a naturally related Gauss curvature. We also…

Complex Variables · Mathematics 2012-10-16 Xiaojun Huang , Shanyu Ji , Brandon Lee

We perform detailed computations of Lie algebras of infinitesimal CR-automorphisms associated to three specific model real analytic CR-generic submanifolds in C^9 by employing differential algebra computer tools -- mostly within the Maple…

Rings and Algebras · Mathematics 2012-12-14 Masoud Sabzevari , Amir Hashemi , Benyamin M. -Alizadeh , Joel Merker

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

We study CR-manifolds of arbitrary CR codimension, mainly focusing on Levi and contact-nondegeneracy and depth. We investigate these and other invariants in the locally homogeneous case, developing a comprehensive theory which establishes…

Differential Geometry · Mathematics 2026-04-22 Stefano Marini , Costantino Medori , Mauro Nacinovich