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Related papers: Open Whitney umbrellas are locally polynomially co…

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The paper considers a class of Lagrangian surfaces in $\mathbb C^2$ with isolated singularities of the unfolded Whitney umbrella type. We prove that generically such a surface is locally polynomially convex near a singular point of this…

Complex Variables · Mathematics 2012-08-24 Rasul Shafikov , Alexandre Sukhov

We obtain local and global results on polynomially convex hulls of Lagrangian and totally real submanifolds of $C^n$ with self-intersections and open Whitney umbrella points.

Complex Variables · Mathematics 2014-03-12 Rasul Shafikov , Alexandre Sukhov

It is shown that a Lagrangian inclusion of a real surface in $\mathbb C^2$ with a standard open Whitney umbrella and double transverse self-intersections is rationally convex.

Complex Variables · Mathematics 2015-02-20 Rasul Shafikov , Alexandre Sukhov

In this paper we discuss a couple of observations related to polynomial convexity. More precisely, (i) We observe that the union of finitely many disjoint closed balls with centres in $\cup_{\theta\in[0,\pi/2]}e^{i\theta}V$ is polynomially…

Complex Variables · Mathematics 2019-09-11 Sushil Gorai

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 give a complete characterization of those disk bundles over surfaces which embed as rationally convex strictly pseudoconvex domains in $\mathbb{C}^2$. We recall some classical obstructions and prove some deeper ones related to symplectic…

Complex Variables · Mathematics 2016-02-05 Stefan Nemirovski , Kyler Siegel

We prove that every polynomially convex arc is contained in a polynomially convex simple closed curve. We also establish results about polynomial hulls of arcs and curves that are locally rectifiable outside a polynomially convex subset.

Complex Variables · Mathematics 2021-06-21 Alexander J. Izzo , Edgar Lee Stout

We consider the following question: Let $S_1$ and $S_2$ be two smooth, totally-real surfaces in $\mathbb{C}^2$ that contain the origin. If the union of their tangent planes is locally polynomially convex at the origin, then is $S_1 \cup…

Complex Variables · Mathematics 2010-03-26 Sushil Gorai

We show that a Lagrangian inclusion in $\mathbb C^2$ with double transverse self-intersection points and standard open Whitney umbrellas is rationally convex. As an application we show that any compact surface $S$, except $S^2$ and $\mathbb…

Complex Variables · Mathematics 2016-11-17 Rasul Shafikov , Alexandre Sukhov

Under certain geometric condition, the surfaces in $\mathbb{C}^2$ with isolated CR singularity at the origin and with cubic lowest degree homogeneous term in its graph near the origin, can be reduced, up to biholomorphism of $\mathbb{C}^2$,…

Complex Variables · Mathematics 2025-01-30 Sushil Gorai

We state that any constant curvature Riemannian metric with conical singularities of constant sign curvature on a compact (orientable) surface $S$ can be realized as a convex polyhedron in a Riemannian or Lorentzian) space-form. Moreover…

Differential Geometry · Mathematics 2010-11-16 François Fillastre

We prove that, if $W \subset \mathbb{R}^n$ is a locally strongly convex body (not necessarily compact), then for any open set $V \supset \partial W$ and $\varepsilon>0$, and $V \supset \partial W$ is open, then there exists a $C^2$ locally…

Classical Analysis and ODEs · Mathematics 2024-10-11 Daniel Azagra , Marjorie Drake , Piotr Hajłasz

In this paper, we first prove that the totally real discs lying in certain Levi flat hypersurfaces are polynomially convex. As applications we prove that the totally real discs lying in the boundary of certain polynomial polyhedra are…

Complex Variables · Mathematics 2023-05-10 Sushil Gorai , Golam Mostafa Mondal

Several results concerning pairs of polynomially convex sets whose union is not even rationally convex are given. It is shown that there is no restriction on how two spaces can be embedded in some $\C^N$ so as to be polynomially convex but…

Complex Variables · Mathematics 2021-08-23 Alexander J. Izzo

We consider curves which go around Whitney umbrella. Then we consider the geodesic and the normal curvatures, ruled surfaces generated by the normal vector and normal developable surfaces with respect to the tangent and bi-tangent vectors…

Differential Geometry · Mathematics 2025-08-22 Masayuki Hara

We study the singularities of the members of the family of height functions on Whitney umbrellas, which is also known as cross-caps, and show that the family of the height functions is a versal unfolding. Moreover, we study local…

Differential Geometry · Mathematics 2012-12-10 Toshizumi Fukui , Masaru Hasegawa

The paper is concerned with the boundary behaviour of polynomially and rationally convex hulls in pseudoconvex domains in $\mathbb{C}^n$. As an application, it is shown that every connected polynomially or rationally convex compact set with…

Complex Variables · Mathematics 2026-05-26 Stefan Nemirovski , Josias Reppekus , Nikolay Shcherbina

Let $C$ be a compact convex subset of $\mathbb{R}^n$, $f:C\to\mathbb{R}$ be a convex function, and $m\in\{1, 2, ..., \infty\}$. Assume that, along with $f$, we are given a family of polynomials satisfying Whitney's extension condition for…

Classical Analysis and ODEs · Mathematics 2019-03-05 Daniel Azagra , Carlos Mudarra

Let K be a connected Lie group and M a Hamiltonian K-manifold. In this paper, we introduce the notion of convexity of M. It implies that the momentum image is convex, the moment map has connected fibers, and the total moment map is open…

Symplectic Geometry · Mathematics 2007-05-23 Friedrich Knop

Let $M$ be a strictly convex smooth connected hypersurface in $\mathbb R^n$ and $\widehat{M}$ its convex hull. We say that $M$ is locally polynomially integrable if the $(n-1)-$ dimensional volumes of the sections of $\widehat M$ by…

Metric Geometry · Mathematics 2021-03-03 Mark Agranovsky
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