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Let $X$ be a Stein manifold of dimension at least 3. Given a compact codimension 2 real analytic submanifold $M$ of $X$, that is the boundary of a compact Levi-flat hypersurface $H$, we study the regularity of $H$. Suppose that the CR…

Complex Variables · Mathematics 2010-08-20 Jiri Lebl

Let $\mathcal{A}$ be a unital associative algebra and $\mathcal{M}$ be an $\mathcal{A}$-bimodule. A linear mapping $\varphi$ from $\mathcal{A}$ into an $\mathcal{A}$-bimodule $\mathcal{M}$ is called a Lie derivation if…

Operator Algebras · Mathematics 2018-06-11 Jun He , Guangyu An

In this article we provide a version of Chow's theorem for real analytic Levi-flat hypersurfaces in the complex projective space $\mathbb{P}^{n}$, $n \geq 2$. More specifically, we prove that a real analytic Levi-flat hypersurface $M…

Complex Variables · Mathematics 2021-12-06 Arturo Fernández-Pérez , Rogério Mol , Rudy Rosas

In this paper, we study positive as well as non-negative and non-trivial gradings on finite dimensional Lie algebras. We give a different proof that the existence of such a grading on a Lie algebra is invariant under taking field…

Rings and Algebras · Mathematics 2016-03-04 Jonas Deré

A locally conformally product (LCP) structure on a compact conformal manifold is a closed non-exact Weyl connection (i.e.~a linear connection which is locally but not globally the Levi-Civita connection of Riemannian metrics in the…

Differential Geometry · Mathematics 2024-04-30 Viviana del Barco , Andrei Moroianu

We address the problem to characterise closed type I subgroups of the automorphism group of a tree. Even in the well-studied case of Burger-Mozes' universal groups, non-type I criteria were unknown. We prove that a huge class of groups…

Group Theory · Mathematics 2016-11-30 Cyril Houdayer , Sven Raum

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

Necessary and sufficient conditions for the exponentiation of finite-dimensional real Lie algebras of linear operators on complete Hausdorff locally convex spaces are obtained, focused on the equicontinuous case - in particular, necessary…

Functional Analysis · Mathematics 2019-11-12 Rodrigo A. H. M. Cabral

In this survey, we report on the state of the art of some of the fundamental problems in the Lie theory of Lie groups modeled on locally convex spaces, such as integrability of Lie algebras, integrability of Lie subalgebras to Lie…

Representation Theory · Mathematics 2015-01-27 Karl-Hermann Neeb

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

Let L be a finite dimensional simple Lie algebra over an algebraically closed field of characteristic p>3. We prove in this paper that if all tori of maximal dimansion in the semisimple p-envelope of L are standard, the L is up to…

Rings and Algebras · Mathematics 2007-05-23 Alexander Premet , Helmut Strade

Normal affine algebraic varieties in characteristic 0 are uniquely determined (up to isomorphism) by the Lie algebra of derivations of their coordinate ring. This is not true without the hypothesis of normality. But, we show that (in…

alg-geom · Mathematics 2008-02-03 Antonio Campillo , Janusz Grabowski , Gerd Müller

Let M be a connected real-analytic hypersurface in two dimensional complex space, $\mathbb C^2$, containing a connected complex hypersurface E, and let f be a smooth CR mapping sending M into another real-analytic hypersurface M' in…

Complex Variables · Mathematics 2007-05-23 Peter Ebenfelt

Let $M \subset {\mathbb{C}}^{n+1}$, $n \geq 2$, be a real codimension two CR singular real-analytic submanifold that is nondegenerate and holomorphically flat. We prove that every real-analytic function on $M$ that is CR outside the CR…

Complex Variables · Mathematics 2018-08-16 Jiri Lebl , Alan Noell , Sivaguru Ravisankar

Let $G$ be a connected Lie group, $C$ be the maximal compact connected subgroup of the center of $G$, and let Aut$(G)$ denote the group of Lie automorphisms of $G$, viewed, canonically, also as a subgroup of GL$(\frak G)$, where $\frak G$…

Group Theory · Mathematics 2025-04-29 S. G. Dani , Riddhi Shah

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

We prove that every local derivation on a finite-dimensional semisimple Lie algebra over an algebraically closed field of characteristic zero is a derivation. We also give examples of finite-dimensional nilpotent Lie algebras $\mathcal{L}$…

Rings and Algebras · Mathematics 2015-08-24 Shavkat Ayupov , Karimbergen Kudaybergenov

We study Deaconu-Renault groupoids corresponding to surjective local homeomorphisms on locally compact, Hausdorff, second countable, totally disconnected spaces, and we characterise when the C*-algebras of these groupoids are AF embeddable.…

Operator Algebras · Mathematics 2024-07-24 Rafael Pereira Lima

Let $X \subset \mathbb{C}^n$ be an algebraic variety, and let $\Lambda \subset \mathbb{C}^n$ be a discrete subgroup whose real and complex spans agree. We describe the topological closure of the image of $X$ in $\mathbb{C}^n / \Lambda$,…

Algebraic Geometry · Mathematics 2022-09-23 Spencer Dembner , Hunter Spink

This paper deals with affine connections on real manifolds. We give a new characterization of flat affine connections on real manifolds by means of certain affine representations of the Lie group of automorphisms preserving the connection.…

Differential Geometry · Mathematics 2018-08-31 Alberto Medina , Omar Saldarriaga , Andres Villabón