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In this paper we continue our study of local rigidity for maps of CR submanifolds of the complex space. We provide a linear sufficient condition for local rigidity of finitely nondegenerate maps between minimal CR manifolds. Furthermore, we…

Complex Variables · Mathematics 2021-06-15 Giuseppe della Sala , Bernhard Lamel , Michael Reiter

We show that every point in a uniformly $2$-nondegenerate CR hypersurface is canonically associated with a model $2$-nondegenerate structure. The $2$-nondegenerate models are basic CR invariants playing the same fundamental role as quadrics…

Complex Variables · Mathematics 2024-04-11 Jan Gregorovič , Martin Kolář , David Sykes

We prove several results concerning automorphism groups of quasismooth complex weighted projective hypersurfaces; these generalize and strengthen existing results for hypersurfaces in ordinary projective space. First, we prove in most cases…

Algebraic Geometry · Mathematics 2024-06-11 Louis Esser

The paper gives a complete description of local automorphism groups for Levi degenerate hypersurfaces of finite type in $\mathbb{C}^2$. We also prove that, with the exception of hypersurfaces of the form $v = |z|^k$, local automorphisms are…

Complex Variables · Mathematics 2015-06-26 Martin Kolar

A method is proposed to obtain examples of smooth CR-manifolds whose local stability group is neither a Lie group nor infinite-dimensional.

Complex Variables · Mathematics 2007-05-23 Sung-Yeon Kim , Dmitri Zaitsev

We study local rigidity properties of holomorphic embeddings of real hypersurfaces in $\mathbb C^2$ into real hypersurfaces in $\mathbb C^3$ and show that infinitesimal conditions imply actual local rigidity in a number of (important)…

Complex Variables · Mathematics 2021-06-15 Giuseppe Della Sala , Bernhard Lamel , Michael Reiter

Motivated by the Shilov boundaries of bounded symmetric domains we consider arbitrary CR-quadrics in a complex linear space (of finite dimension) that have a certain symmetry property. For these the non-affine local CR-automorphisms have a…

Complex Variables · Mathematics 2009-07-28 Wilhelm Kaup

We investigate the size of fixed point sets of automorphisms of bounded domains in $\mathbb{C}^n$. In one complex variable, a nontrivial automorphism has at most two fixed points, but in higher dimensions fixed point sets need not be…

Complex Variables · Mathematics 2026-04-10 Bharathi Thiruvengadam , Jaikrishnan Janardhanan

A few facts concerning the phrase "the automorphism groups become larger at special points of the moduli of K3 surfaces" are presented. It is also shown that the automorphism groups are of infinite order over a dense subset in any…

Algebraic Geometry · Mathematics 2007-05-23 Keiji Oguiso

We construct normal forms for Levi degenerate hypersurfaces of finite type in $\mathbb C^2$. As one consequence, an explicit solution to the problem of local biholomorphic equivalence is obtained. Another consequence determines the…

Complex Variables · Mathematics 2007-05-23 Martin Kolar

In this article the notion of ultradifferentiable CR manifold is introduced and an ultradifferentiable regularity result for finitely nondegenerate CR mappings is proven. Here ultradifferentiable means with respect to Denjoy-Carleman…

Complex Variables · Mathematics 2018-08-09 Stefan Fürdös

We consider a problem whether a CR mapping of a generic manifold in complex space is uniquely determined by its finite jet at a point, which is referred to as finite jet determination. We derive the finite jet determination for CR mappings…

Complex Variables · Mathematics 2022-07-13 Alexander Tumanov

For any real-analytic hypersurface M in complex euclidean space of dimension >= 2 which does not contain any complex-analytic subvariety of positive dimension, we show that for every point p in M the local real-analytic CR automorphisms of…

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

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 consider locally homogeneous $CR$ manifolds and show that, under a condition only depending on their underlying contact structure, their $CR$ automorphisms form a finite dimensional Lie group.

Differential Geometry · Mathematics 2017-06-13 Stefano Marini , Costantino Medori , Mauro Nacinovich , Andrea Spiro

In this note, we consider models in $\mathbb C^2$. The purpose of this note is twofold. We first show a characterization of models in $\mathbb C^2$ by their noncompact automorphism groups. Then we give an explicit description for…

Complex Variables · Mathematics 2014-10-09 Ninh Van Thu , Mai Anh Duc

In this paper, we study the real hypersurfaces $M$ in $\mathbb C^2$ at points $p\in M$ of infinite type. The degeneracy of $M$ at $p$ is assumed to be the least possible, namely such that the Levi form vanishes to first order in the CR…

Complex Variables · Mathematics 2015-10-21 Peter Ebenfelt , Bernhard Lamel , Dmitri Zaitsev

In a recent paper, the author and I. Zelenko introduce the concept of modified CR symbols for organizing local invariants of $2$-nondegenerate CR structures. In this paper, we consider homogeneous hypersurfaces in $\mathbb{C}^4$, a natural…

Differential Geometry · Mathematics 2023-06-09 David Sykes

We show that smooth hypersurfaces in complex projective spaces with automorphism groups of maximum size are isomorphic to Fermat hypersurfaces, with a few exceptions. For the exceptions, we give explicitly the defining equations and…

Algebraic Geometry · Mathematics 2025-01-30 Song Yang , Xun Yu , Zigang Zhu

We study the connected component of the automorphism group of a cubic hypersurface over complex numbers. When the cubic hypersurface has nonzero Hessian, this group is usually small. But there are examples with unusually large automorphism…

Algebraic Geometry · Mathematics 2016-12-30 Jun-Muk Hwang