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We introduce the notion of a subregular subalgebra, which we believe is useful for classification of subalgebras of Lie algebras. We use it to construct a non-regular invariant generalized complex structure on a Lie group. As an…

Algebraic Geometry · Mathematics 2017-01-03 Evgeny Mayanskiy

In (Arnold, 1985), V.I. Arnold has obtained normal forms and has developed a classifier for, in particular, all isolated hypersurface singularities over the complex numbers up to modality 2. Building on a series of 105 theorems, this…

Algebraic Geometry · Mathematics 2019-08-15 Janko Boehm , Magdaleen S. Marais , Gerhard Pfister

We give a method to construct explicitly a supersingular curve of given genus g in characteristic 2.

alg-geom · Mathematics 2008-02-03 Gerard van der Geer , Marcel van der Vlugt

We construct closed symplectic manifolds for which spherical classes generate arbitrarily large subspaces in 2-homology, such that the first Chern class and cohomology class of the symplectic form both vanish on all spherical classes. We…

Differential Geometry · Mathematics 2016-09-07 Robert E. Gompf

For globally subanalytic manifolds we define de Rham complexes of globally subanalytic differential forms and of constructible differential forms. Whereas the de Rham theorem does not hold for the former in the non-compact case, it does…

Logic · Mathematics 2025-08-06 Annette Huber , Tobias Kaiser , Abhishek Oswal

Searching normal forms for real analytic submanifolds of C^n involves convergence problems. In 1983, J.K. Moser and S.M. Webster provided examples of real analytic surfaces in C^2 having an isolated hyperbolic (in the sense of E. Bishop)…

Complex Variables · Mathematics 2007-05-23 Joël Merker

We consider the sphere $\Sph^{2n+1}$ equipped with its standard CR structure. In this paper we construct explicit contact forms on $\Sph^{2n+1}\setminus \Sph^{2k+1}$, which are conformal to the standard one and whose related Webster metrics…

Differential Geometry · Mathematics 2019-08-29 Chiara Guidi , Ali Maalaoui , Vittorio Martino

This paper first studies the regularity of conformal homeomorphisms on smooth locally embeddable strongly pseudoconvex CR manifolds. Then moduli of curve families are used to estimate the maximal dilatations of quasiconformal…

Complex Variables · Mathematics 2009-09-25 Puqi Tang

We smooth the singularities of a strictly hyperbolized smooth cube manifold.

Differential Geometry · Mathematics 2014-12-01 Pedro Ontaneda

The principles behind the sharp, singular structures in a crumpled sheet are well understood. Here we discuss more general ways of exploiting such sharp structures to control the shape of a sheet by deforming or forcing it elsewhere. Often,…

Soft Condensed Matter · Physics 2025-03-24 Thomas A. Witten , Anna Movsheva

Let M be a closed simply connected 2n-dimensional manifold. The present paper is concerned with the cohomology of classifying spaces of connected groups of homeomorphisms of M.

Algebraic Topology · Mathematics 2010-10-15 Jarek Kędra

We prove a formality theorem for algebraic objects internal to smooth complex varieties that are not compact but whose mixed Hodge structure has a certain purity property.

Algebraic Topology · Mathematics 2017-03-27 Geoffroy Horel

We study sheaves of differential forms and their cohomology in the h-topology. This allows to extend standard results from the case of smooth varieties to the general case. As a first application we explain the case of singularities arising…

Algebraic Geometry · Mathematics 2014-05-15 Annette Huber , Clemens Jörder

We introduce a new class of singular complex manifolds and we develop a degenerate Kodaira-Hodge theory for this class of singular manifolds.

Differential Geometry · Mathematics 2025-04-30 Alireza Bahraini

Codimension 2 contact submanifolds are the natural generalization of transverse knots to contact manifolds of arbitrary dimension. In this paper, we construct new invariants of codimension 2 contact submanifolds. Our main invariant can be…

Symplectic Geometry · Mathematics 2024-03-06 Laurent Côté , François-Simon Fauteux-Chapleau

We investigate the non-diagonal normal forms of a quadratic form on R^n, in particular for n=3. For this case it is shown that the set of normal forms is the closure of a 5-dimensional submanifold in the 6-dimensional Grassmannian of…

Representation Theory · Mathematics 2010-02-23 Bernhard Kroetz , Henrik Schlichtkrull

A simple characterization is given of open subsets of a complex surface that smoothly perturb to Stein open subsets. As applications, complex 2-space C^2 contains domains of holomorphy (Stein open subsets) that are exotic R^4's, and others…

Geometric Topology · Mathematics 2014-08-06 Robert E. Gompf

It is known that complex constant mean curvature ({\sc CMC} for short) immersions in $\mathbb C^3$ are natural complexifications of {\sc CMC}-immersions in $\mathbb R^3$. In this paper, conversely we consider {\it real form surfaces} of a…

Differential Geometry · Mathematics 2012-03-09 Shimpei Kobayashi

We formulate and prove a twofold generalisation of Lie's second theorem that integrates homomorphisms between formal group laws to homomorphisms between Lie groups. Firstly we generalise classical Lie theory by replacing groups with…

Category Theory · Mathematics 2016-05-25 Matthew Burke

We determine a 2-codimensional CR-structure on the slit tangent bundle $T_0M$ of a Finsler manifold $(M, F)$ by imposing a condition regarding the almost complex structure $\Psi$ associated to $F$ when restricted to the structural…

Differential Geometry · Mathematics 2016-08-11 Mircea Crasmareanu , Laurian-Ioan Pişcoran