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It is known that locally compact groups approximable by finite ones are unimodular, but this condition is not sufficient, for example, the simple Lie groups are not approximable by finite ones as topological groups. In this paper the…

Group Theory · Mathematics 2007-05-23 L. Yu. Glebsky , E. I. Gordon

For each positive integer Q there exists a path connected metric compactum X such that the Qth-homotopy group of X is compactly generated but not a topological group (with the quotient topology).

Algebraic Topology · Mathematics 2011-06-01 Paul Fabel

We give a very simple construction of the string 2-group as a strict Fr\'echet Lie 2-group. The corresponding crossed module is defined using the conjugation action of the loop group on its central extension, which drastically simplifies…

Differential Geometry · Mathematics 2023-05-23 Matthias Ludewig , Konrad Waldorf

We describe the representation theory of loop groups in terms of K-theory and noncommutative geometry. This is done by constructing suitable spectral triples associated with the level l projective unitary positive-energy representations of…

Operator Algebras · Mathematics 2018-10-09 Sebastiano Carpi , Robin Hillier

We exhibit a pseudogroup of smooth local transformations of the real line which is compactly generated, but not realizable as the holonomy pseudogroup of a foliation of codimension 1 on a compact manifold. The proof relies on a description…

Geometric Topology · Mathematics 2021-01-06 Gael Meigniez

This paper studies the question of when a loop $\phi$ in the group Symp$(M,\omega)$ of symplectomorphisms of a symplectic manifold $(M,\omega)$ is isotopic to a loop that is generated by a time-dependent Hamiltonian function. (Loops with…

dg-ga · Mathematics 2007-05-23 François Lalonde , Dusa McDuff , Leonid Polterovich

We show that the class of connected, simple Lie groups that have non-vanishing third-degree continuous cohomology with trivial $\mathbb{R}$-coefficients consists precisely of all simple complex Lie groups and of…

Group Theory · Mathematics 2022-01-26 Carlos De La Cruz Mengual

We give a full classification of Lie algebras of specific type in complexified Clifford algebras. These sixteen Lie algebras are direct sums of subspaces of quaternion types. We obtain isomorphisms between these Lie algebras and classical…

Mathematical Physics · Physics 2024-12-24 D. S. Shirokov

In this paper we construct infinitely many examples of a Riemannian submersion from a simple, compact Lie group $G$ with bi-invariant metric onto a smooth manifold that cannot be a quotient of $G$ by a group action. This partially addresses…

Differential Geometry · Mathematics 2009-10-23 Martin Kerin , Krishnan Shankar

Moufang loops are one of the best-known generalizations of groups. There is only one countable family of nonassociative finite simple Moufang loops, arising from the split octonion algebras. We prove that every member of this family is…

Group Theory · Mathematics 2007-05-23 Petr Vojtěchovský

This note is concerned with the geometric classification of connected Lie groups of dimension three or less, endowed with left-invariant Riemannian metrics. On the one hand, assembling results from the literature, we give a review of the…

Group Theory · Mathematics 2018-11-07 Katrin Fässler , Enrico Le Donne

A locally compact contraction group is a pair (G,f) where G is a locally compact group and f an automorphism of G which is contractive in the sense that the forward orbit under f of each g in G converges to the neutral element e, as n tends…

Group Theory · Mathematics 2018-04-05 Helge Glockner , George A. Willis

The article is devoted to the investigation of groups of diffeomorphisms and loops of manifolds over ultra-metric fields of zero and positive characteristics. Different types of topologies are considered on groups of loops and…

Group Theory · Mathematics 2018-12-18 S. V. Ludkovsky

We classify connected Lie groups which are locally isomorphic to generalized Heisenberg groups. For a given generalized Heisenberg group $N$, there is a one-to-one correspondence between the set of isomorphism classes of connected Lie…

Differential Geometry · Mathematics 2007-05-23 Hiroshi Tamaru , Hisashi Yoshida

Right groups are direct products of right zero semigroups and groups and they play a significant role in the semilattice decomposition theory of semigroups. Right groups can be characterized as associative right quasigroups (magmas in which…

Group Theory · Mathematics 2012-10-01 Michael K. Kinyon , Aleksandar Krapež , J. D. Phillips

Given a simple Lie group G of rank 1, we consider compact pseudo-Riemannian manifolds (M,g) of signature (p,q) on which G can act conformally. Precisely, we determine the smallest possible value for the index min(p,q) of the metric. When…

Differential Geometry · Mathematics 2020-05-20 Vincent Pecastaing

We contribute to the classification of toroidal circle planes and flat Minkowski planes possessing three-dimensional connected groups of automorphisms. When such a group is an almost simple Lie group, we show that it is isomorphic to…

Geometric Topology · Mathematics 2026-03-17 Brendan Creutz , Duy Ho , Günter F. Steinke

Given a simplicial complex $X$, we construct a simplicial complex $\Omega X$ that may be regarded as a combinatorial version of the based loop space of a topological space. Our construction explicitly describes the simplices of $\Omega X$…

Algebraic Topology · Mathematics 2025-07-17 Gregory Lupton , Jonathan Scott

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

The present paper links the representation theory of Lie groupoids and infinite-dimensional Lie groups. We show that smooth representations of Lie groupoids give rise to smooth representations of associated Lie groups. The groups envisaged…

Group Theory · Mathematics 2019-05-21 Habib Amiri , Alexander Schmeding