Computes the component group of arbitrary real algebraic groups.
problem Computing the component group of arbitrary real algebraic groups.
method Structure results on algebraic groups and Galois cohomology methods.
result The group of connected components π0G(R) is an elementary Abelian 2-group. Builds geometric structures for algebraic groups over real closed fields.
problem Characterizing and decomposing algebraic groups over specific valued fields.
method Real algebraic geometry to construct and analyze affine buildings.
result Computed stabilizers and obtained group decompositions.
The paper studies spaces of non-compact real algebraic curves and their uniformisation.
problem Understanding the spaces of non-compact real algebraic curves and their uniformisation.
method Construction of spaces of non-compact real algebraic curves and description of their connected components using Fuchsian groups.
result Any connected component of the spaces of non-compact real algebraic curves is homeomorphic to a quotient of a finite-dimensional real vector space by a discrete group.
We prove that a polar orthogonal representation of a real reductive algebraic group has the same closed orbits as the isotropy representation of a pseudo-Riemannian symmetric space. We also develop a partial structural theory of polar orthogonal representations of real reductive algebraic groups which slightly generali…
Real Lie groups' invariant theory matches that of their affine counterparts.
problem Matching invariant theory of real Lie groups with affine groups.
method Simple remark showing coincidence.
result Invariant theory of real Lie groups equals that of their affine counterparts.
Study on real algebraic curves' moduli spaces using a new complex.
problem Understanding the topology of moduli spaces of real algebraic curves.
method Defined a new complex, the ABC-complex, to encode intersection patterns. result Showed that mapping class groups are virtual duality groups and deduced orbifold homotopy group results.
Computes the component group of real reductive groups.
problem Computing the component group of real reductive groups.
method Using structure results for real loci of algebraic groups and Galois cohomology.
result Explicit elements representing all connected components of G(R). The orbit decomposition is given under the automorphism group on the real split Jordan algebra of all hermitian matrices of order three corresponding to any real split composition algebra, or the automorphism group on the complexification, explicitly, in terms of the cross product of H. Freudenthal and the characterist…
On realizations of the complex Lie groups (F4,R)C,(E6,R)C,(E7,R)C,(E8,R)C and those compact real forms F4,R,E6,R,E7,R,E8,Rmath.DG The paper explores alternative definitions of complex Lie groups using real numbers.
problem Defining complex Lie groups using real numbers.
method Replacing Cayley algebra with real numbers to define groups.
result Determined the structure of complex and compact Lie groups.
Every finite dimensional real representation of a compact real semisimple Lie algebra determines a metric 2-step nilpotent Lie algebra and a corresponding simply connected metric 2-step nilpotent Lie group N. We study the differential geometry of N using representation theory of the complexified complex semisimple Lie …
The paper classifies orbit closures of symplectic Lie algebras.
problem Classifying orbit closures of symplectic Lie algebras under the action of Sp(4,R). method Analyzing the natural action of Sp(4,R) on the set of 4-dimensional Lie algebras with symplectic structures. result A complete classification of orbit closures of 4-dimensional symplectic Lie algebras.
Constructs a topological cover of real line's multiplicative group.
problem Topological cover of real line's multiplicative group.
method Homological algebra, 2D Lorentz geometry, high-school trigonometry.
result Interesting topological cover constructed.
New invariant distinguishes real algebraic surfaces.
problem Distinguishing real algebraic surfaces up to birational diffeomorphism.
method Introducing real (logarithmic)-Kodaira dimension.
result Constructs infinite families of non-birationally diffeomorphic surfaces.
New braid group actions on n-adic integers linked to real algebraic links.
problem Understanding braid group actions on n-adic integers. method Constructing an infinite tower of covering spaces over configuration spaces and associating braids to infinite sequences of braids.
result An infinite family of braids close to real algebraic links.
Bi-Lipschitz rigidity theorem for dense subgroups of algebraic groups.
problem Characterizing dense subgroups of algebraic groups.
method Bi-Lipschitz rigidity theorem for Zariski dense discrete subgroups.
result No C1-smooth slim limit set for higher rank semisimple algebraic groups. Study algebraic K-theory for specific groups of non-orientable surfaces.
problem Algebraic K-theory of group rings for specific non-orientable surface groups.
method Detailed analysis of group rings and algebraic K-theory.
result General formula for algebraic K-theory groups of mapping class groups of non-orientable surfaces.
On realizations of the complex Lie groups (E6,R)C,(E6,C)C,(E6,H)C and those real formsmath.RA The paper explores different realizations of complex Lie groups using various number fields.
problem Defining and understanding Lie groups with different number fields.
method Using Cayley algebras and fields of real numbers, complex numbers, split complex numbers, quaternions, and split quaternions to define and study Lie groups.
result The structure of Lie groups (E6,R)C,(E6,C)C,(E6,H)C and their real forms are determined. The paper studies invariant measures for specific actions in algebraic groups.
problem Investigating invariant measures for horospherical actions and Anosov groups.
method Analyzing the space of invariant measures for NM-actions on Γ\G. result The space of invariant measures is homeomorphic to RextrankG−1. We give a survey of the theory of surface braid groups and the lower algebraic K-theory of their group rings. We recall several definitions and describe various properties of surface braid groups, such as the existence of torsion, orderability, linearity, and their relation both with mapping class groups and with the h…
Criterion for nilpotent Lie groups to have nilsolitons.
problem Existence of nilsolitons in nilpotent Lie groups.
method Algebraic criterion for nilpotent Lie algebras, proving necessary and sufficient condition for nilsolitons.
result Criterion provides a necessary and sufficient condition for nilpotent Lie groups to admit nilsolitons.
Study extends JB-algebra structure group results to infinite dimensions.
problem Extend results for real Jordan algebras to infinite dimensional JB-algebras.
method Prove structure groups, cone preserving groups, and automorphism groups are embedded Banach-Lie groups; describe components via cones, isotopes, and central projections; apply to special JB-algebra of self-adjoint operators.
result Full description of components of structure group and automorphism group, including their Banach-Lie algebras and connected components.
Analytic curves linked to algebraic ones via Schottky groups.
problem Moving between analytic and algebraic representations of Riemann surfaces.
method Identifying Riemann surfaces with Schottky groups and constructing families of non-hyperelliptic surfaces.
result Construction of families of non-hyperelliptic surfaces with specific properties.
It is well-known that classical two-dimensional topological field theories are in one-to-one correspondence with commutative Frobenius algebras. An important extension of classical two-dimensional topological field theories is provided by open-closed two-dimensional topological field theories. In this paper we extend o…
Uniform Jordan property proven for Lie groups and complex space transformations.
problem Proving Jordan property for Lie groups and complex space transformations.
method Analyzing families of Lie groups and using algebraic groups properties.
result Uniform Jordan property established for Lie groups and complex space transformations.
Study on Lie groups and their geometric properties.
problem Classifying 4D Lie algebras and analyzing their geometric structures.
method Investigation of 4D Lie groups as manifolds, focusing on indecomposable real Lie algebras with two parameters and their almost hypercomplex structures with Hermitian-Norden metrics.
result Geometric characteristics of almost hypercomplex manifolds derived from 4D Lie groups.
Improves an existing algorithm for computing algebraic set homology groups.
problem Efficiently computing the homology groups of algebraic or semi-algebraic sets.
method Adaptive grid algorithm on the unit sphere.
result Practical improvement of an existing algorithm for homology computation.
The paper characterizes flat affine connections on manifolds and Lie groups.
problem Characterizing flat affine connections on manifolds and Lie groups.
method New characterization through affine representations of automorphisms.
result Existence of a Lie group with a flat affine bi-invariant connection.
Generic Hitchin representations avoid hyperplanes in Lie algebras.
problem Properties of Hitchin representations in Lie algebras.
method Defined J(ρ) and used hyperplanes in Lie algebras to show J(ρ)∩H=∅. result Generic G-Hitchin representations avoid hyperplanes in the Lie algebra of G. Maximal Laplacian algebras applied to invariant theory solved inverse problems.
problem Maximality of Laplacian algebras and their applications in invariant theory.
method Proof of maximality and applications to classical invariant theory.
result Introduction of generalized polarizations and if-and-only-if criterion.
Lie groups of automorphisms of cotangent bundles of Lie groups are completely characterized and interesting results are obtained. We give prominence to the fact that the Lie groups of automorphisms of cotangent bundles of Lie groups are super symmetric Lie groups. In the cases of orthogonal Lie lgebras, semi-simple Lie…
We formulate and prove that there are "abundant" in nilpotent orbits in real semisimple Lie algebras, in the following sense. If S denotes the collection of hyperbolic elements corresponding the weighted Dynkin diagrams coming from nilpotent orbits, then S span the maximally expected space, namely, the (-1)-eigenspace …
The paper classifies orbits of semisimple elements in real semisimple Lie algebras.
problem Classifying orbits of semisimple elements in real semisimple Lie algebras.
method Case by case analysis of complex numbers and Galois cohomology for real numbers.
result Characterization of orbits with real representatives.
The main goal is to classify 4-dimensional real Lie algebras $\g$ which admit a para-hypercomplex structure. This is a step toward the classification of Lie groups admitting the corresponding left-invariant structure and therefore possessing a neutral, left-invariant, anti-self-dual metric. Our study is related to the …
In this article, we present an integration of any real finite-dimensional Leibniz algebra as a Lie rack which reduces in the particular case of a Lie algebra to the ordinary connected simply connected Lie group. The construction is not functorial.
New non-solvable Lie groups found with negative Ricci curvature.
problem Finding new Lie groups with negative Ricci curvature.
method Using a general construction from a previous article, the authors produce metric Lie algebras with negative Ricci curvature for compact semisimple Lie algebras.
result The constructed Lie algebras have negative Ricci curvature for all but finitely many finite-dimensional irreducible representations of the Lie algebra.
The paper studies algebraic integer relations and sequences converging to 4.
problem Investigating algebraic integer relations and convergence of sequences.
method Constructing a generalized Farey graph for the subgroup Gα and analyzing its properties. result A sequence of algebraic integers converges to 4, each corresponding to a non-free group of rank 2.
We give necessary conditions for certain real analytic tube generic submanifolds in C^n to be locally algebraizable. As an application, we exhibit families of real analytic non locally algebraizable tube generic submanifolds in C^n. During the proof, we show that the local CR automorphism group of a minimal, finitely n…
Let J1 be the real form of complex simple Jordan algebra with the automorphism group G of type F4(−20). Explicitly, we give the orbit decomposition of J1 under the action of G and determine the Lie group structure of stabilizer for each G-orbit on J1.
Conditions for exponentiating Lie algebras on complete locally convex spaces are established.
problem Conditions for exponentiating Lie algebras of linear operators on complete locally convex spaces.
method Focus on equicontinuous case, establishing necessary conditions for exponentiation to compact Lie groups.
result Necessary conditions for exponentiation to compact Lie groups are established.
We classify real 6-dimensional nilpotent Lie algebras for which the corresponding Lie group has a left-invariant complex structure, and estimate the dimensions of moduli spaces of such structures.
A study is made of real Lie algebras admitting a hypersymplectic structure, and we provide a method to construct such hypersymplectic Lie algebras. We use this method in order to obtain the classification of all hypersymplectic structures on four-dimensional Lie algebras, and we describe the associated metrics on the c…
We consider actions of non-compact simple Lie groups preserving an analytic rigid geometric structure of algebraic type on a compact manifold. The structure is not assumed to be unimodular, so an invariant measure may not exist. Ergodic stationary measures always exist, and when such a measure has full support, we show…
Study complex deformations of the circle using group cohomology and Virasoro algebra.
problem Complexification of circle diffeomorphism group and its geometric properties.
method Real-analytic maps, group cohomology, Witt algebra, Frölicher structures.
result Virasoro uniformization theorem for moduli spaces of Riemann surfaces.
Survey recent constructions of cyclic cocycles for Lie groups.
problem Higher index theory for proper cocompact G-actions. method Constructions of cyclic cocycles on Harish-Chandra Schwartz algebra.
result Applications to higher index theory.
A special symplectic Lie group is a triple (G,ω,∇) such that G is a finite-dimensional real Lie group and ω is a left invariant symplectic form on G which is parallel with respect to a left invariant affine structure ∇. In this paper starting from a special symplectic Lie group we show how to ``defo…
Investigates properties of moment maps and stratifications on Lie groups.
problem Understanding moment maps and stratifications on real reductive Lie groups.
method Functorial, algebraic approach to moment map and Kirwan-Ness stratification.
result Properties and properties of moment maps and stratifications established.
Constructs real algebraic functions with specified preimages.
problem Reconstructing smooth functions with prescribed preimages.
method Using real algebraic functions and techniques from singularity theory and differential topology.
result Constructs examples of real algebraic functions with specified preimages.
Infinite volume requires no atoms at the bottom of the spectrum for certain groups.
problem Determining conditions for infinite volume in certain algebraic groups.
method Analyzing the spectral properties of Laplace operators on symmetric spaces.
result The bottom of the L2-spectrum being an atom is necessary and sufficient for finite volume.