English
Related papers

Related papers: Normal Forms and Degenerate CR Singularities

200 papers

By constructing an ODE through a kind of meromorphic 1-forms, we will give an explicit construction of a kind of conformal metrics of constant curvature on Riemann surfaces with singularities. As an application, we will classify constant…

Differential Geometry · Mathematics 2022-04-13 Zhiqiang Wei

We prove necessary and sufficient conditions for a smooth surface in a 4-manifold X to be pseudoholomorphic with respect to some almost complex structure on X. This provides a systematic approach to the construction of pseudoholomorphic…

Differential Geometry · Mathematics 2007-05-23 Christian Bohr

A theorem of Mumford states that, on complex surfaces, any normal isolated singularity whose link is diffeomorphic to a sphere is actually a smooth point. While this property fails in higher dimensions, McLean asks whether the contact…

Algebraic Geometry · Mathematics 2017-01-24 Tommaso de Fernex , Yu-Chao Tu

We consider normal compact surfaces $Y$ obtained from a minimal class VII surface $X$ by contraction of a cycle $C$ of $r$ rational curves with $C^2<0$. Our main result states that, if the obtained cusp is smoothable, then $Y$ is globally…

Complex Variables · Mathematics 2020-03-02 Georges Dloussky , Andrei Teleman

It is proved that any smooth manifold $\mathcal M$ of dimension $m$ admits a smooth polynomially convex embedding into $\mathbb C^n$ when $n\geq \lfloor 5m/4\rfloor$. Further, such embeddings are dense in the space of smooth maps from…

Complex Variables · Mathematics 2025-04-03 Purvi Gupta , Rasul Shafikov

Given a manifold M with a submanifold N, the deformation space D(M,N) is a manifold with a submersion to R whose zero fiber is the normal bundle, and all other fibers are equal to M. This article uses deformation spaces to study the local…

Differential Geometry · Mathematics 2020-02-19 Francis Bischoff , Henrique Bursztyn , Hudson Lima , Eckhard Meinrenken

We consider a CMC hypersurface with an isolated singular point at which the tangent cone is regular, and such that, in a neighbourhood of said point, the hypersurface is the boundary of a Caccioppoli set that minimises the standard…

Differential Geometry · Mathematics 2025-10-09 Costante Bellettini , Konstantinos Leskas

An explicit classification of simply connected compact homogeneous CR manifolds G/L of codimension one, with non-degenerate Levi form, is given. There are three classes of such manifolds: a) the standard CR homogeneous manifolds which are…

Differential Geometry · Mathematics 2007-05-23 Dmitry V. Alekseevsky , Andrea F. Spiro

For each $k\geq2$, we construct two families of surfaces with constant mean curvature $H$ for $H\in[0,1/2]$ in $\Sigma(\kappa)\times\R$ where $\kappa+4H^2\leq0$. The surfaces are invariant under $2\pi/k$-rotations about a vertical fiber of…

Differential Geometry · Mathematics 2013-06-04 Julia Plehnert

This article is a summary of the author's unpublished Ph.D thesis. Its purpose is to generalise a construction by H. Cassens and P. Slodowy of the semiuniversal deformations of the simple singularities of type $A_r$, $D_r$, $E_6$, $E_7$ and…

Representation Theory · Mathematics 2019-01-15 Antoine Caradot

In this paper we construct a large class of new normal forms for Levi-nondegenerate real hypersurfaces in complex spaces. We adopt a general approach illustrating why these normal forms are natural and which role is played by the celebrated…

Complex Variables · Mathematics 2015-02-16 Dmitri Zaitsev

In this paper we study a neighborhood of generic singularities formed by mean curvature flow (MCF). We limit our consideration to the singularities modelled on $\mathbb{S}^3\times\mathbb{R}$ because, compared to the cases…

Differential Geometry · Mathematics 2021-07-27 Gang Zhou

Francesco Severi showed that equisingular families of plane nodal curves are T-smooth, i.e. smooth of the expected dimension, whenever they are non-empty. For families with more complicated singularities this is no longer true. Given a…

Algebraic Geometry · Mathematics 2009-07-28 Thomas Keilen

Any singular level of a completely integrable system (c.i.s.) with non-degenerate singularities has a singular affine structure. We shall show how to construct a simple c.i.s. around the level, having the above affine structure. The…

Symplectic Geometry · Mathematics 2008-07-31 Carlos Currás-Bosch

Questions related to deformations of germs of finite morphisms of smooth surfaces are discussed. A classification of the four-sheeted germs of finite covers $F: (U,o')\to (V,o)$ is given up to smooth deformations, where $(U,o')$ and $(V,o)$…

Algebraic Geometry · Mathematics 2019-01-16 Vik. S. Kulikov

In this article we study quotients of deformations of simple singularities, and attempt to characterize them in terms of subsystems of simple root systems. The quotient of a semiuniversal deformation of a simple singularity of inhomogeneous…

Representation Theory · Mathematics 2018-07-26 Antoine Caradot

We investigate geometric properties of surfaces given by certain formulae. In particular, we calculate the singular curvature and the limiting normal curvature of such surfaces along the set of singular points consisting of singular points…

Differential Geometry · Mathematics 2020-03-25 Yoshiki Matsushita , Takuya Nakashima , Keisuke Teramoto

We present a construction of the chiral de Rham complex over an algebraic surface with at most rational singularities of $A_n$-type. An explicit formula for the character of the chiral structure sheaf is also provided.

Quantum Algebra · Mathematics 2025-07-30 Xi-Chuan Tan

A model describing cell membranes as optimal shapes with regard to the $L^2$-deficit of their mean curvature to a given constant called spontaneous curvature is considered. It is shown that the corresponding energy functional is lower…

Differential Geometry · Mathematics 2023-11-01 Christian Scharrer

We prove that smooth cube manifolds have normal smooth structures.

Geometric Topology · Mathematics 2016-09-21 Pedro Ontaneda