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We explicitly show that symmetric Frobenius structures on a finite-dimensional, semi-simple algebra stand in bijection to homotopy fixed points of the trivial SO(2)-action on the bicategory of finite-dimensional, semi-simple algebras,…

Quantum Algebra · Mathematics 2017-07-26 Jan Hesse , Christoph Schweigert , Alessandro Valentino

We define for a topological group G and a family of subgroups F two versions for the classifying space for the family F, the G-CW-version E_F(G) and the numerable G-space version J_F(G). They agree if G is discrete, or if G is a Lie group…

Geometric Topology · Mathematics 2007-05-23 Wolfgang Lueck

We give different perspectives on the notion of shape for condensed anima. We prove that it recovers more classical notions of shape for topological spaces in the cases of all paracompact compactly generated spaces and all locally…

Algebraic Topology · Mathematics 2026-05-11 Catrin Mair

Group elements of SU(2) are expressed in closed form as finite polynomials of the Lie algebra generators, for all definite spin representations of the rotation group. The simple explicit result exhibits connections between group theory,…

Mathematical Physics · Physics 2017-03-07 Thomas L. Curtright , David B. Fairlie , Cosmas K. Zachos

This self-contained paper is part of a series \cite{FF2,FF3} on actions by diffeomorphisms of infinite groups on compact manifolds. The two main results presented here are: 1) Any homomorphism of (almost any) mapping class group or…

Dynamical Systems · Mathematics 2016-09-07 Benson Farb , John Franks

Homogeneous superspaces arising from the general linear supergroup are studied within a Hopf algebraic framework. Spherical functions on homogeneous superspaces are introduced, and the structures of the superalgebras of the spherical…

Representation Theory · Mathematics 2009-02-03 Ruibin Zhang , Yi Ming Zou

Suppose that a finite solvable group $G$ acts faithfully, irreducibly and quasi-primitively on a finite vector space $V$, and $G$ is not metacyclic. Then $G$ always has a regular orbit on $V$ except for a few "small" cases. We completely…

Group Theory · Mathematics 2021-12-15 Derek Holt , Yong Yang

We prove that bounded conciseness is a closed property in the space of marked groups. As a consequence, we reformulate a conjecture of Fern\'andez-Alcober and Shumyatsky [7] about conciseness in the class of residually finite groups.

Group Theory · Mathematics 2025-02-10 Federico Berlai

In this paper, we study the structure of homogeneous subgroups of the homeomorphism group of the sphere, which are defined as closed groups of homeomorphisms of the sphere that contain the rotation group. We prove two structure theorems…

Geometric Topology · Mathematics 2015-02-16 Ferry Kwakkel , Fabio Tal

We classify simple groups that act by birational transformations on compact complex K\"ahler surfaces. Moreover, we show that every finitely generated simple group that acts non-trivially by birational transformations on a projective…

Algebraic Geometry · Mathematics 2018-02-27 Christian Urech

We prove that any isotropic positive definite function on the sphere can be written as the spherical self-convolution of an isotropic real-valued function. It is known that isotropic positive definite functions on d-dimensional Euclidean…

Probability · Mathematics 2013-10-29 Johanna Ziegel

We study new families of curves that are suitable for efficiently parametrizing their moduli spaces. We explicitly construct such families for smooth plane quartics in order to determine unique representatives for the isomorphism classes of…

Algebraic Geometry · Mathematics 2019-02-06 Reynald Lercier , Christophe Ritzenthaler , Florent Rovetta , Jeroen Sijsling

Assume $(X, \omega)$ is a compact symplectic manifold with a Hamiltonian compact Lie group action and the zero in the Lie algebra is a regular value of the moment map $\mu$. We prove that a finite energy symplectic vortex exponentially…

Symplectic Geometry · Mathematics 2017-07-27 Bohui Chen , Bai-Ling Wang , Rui Wang

Let G be a compact Lie group. By work of Chataur and Menichi, the homology of the space of free loops in the classifying space of G is known to be the value on the circle in a homological conformal field theory. This means in particular…

Algebraic Topology · Mathematics 2015-06-01 Richard Hepworth , Anssi Lahtinen

This paper develops some general results about actions of finite groups on (infinite) abelian groups in the finite Morley rank category. They are linked to a range of problems on groups of finite Morley rank discussed in [16]. Crucially,…

Group Theory · Mathematics 2024-07-24 Alexandre Borovik

Recall that a pseudofree group action on a space is one whose singular set consists only of isolated points. In this paper, we classify all of the finite groups which admit pseudofree actions on S^2 x S^2. The groups turn out to be exactly…

Geometric Topology · Mathematics 2011-11-10 Michael P. McCooey

We construct discrete and faithful representations into the isometry group of a hyperbolic space of the fundamental groups of acute negatively curved even-sided polygons of finite groups.

Group Theory · Mathematics 2014-11-11 Michael Kapovich

We consider orientation-preserving actions of a finite group G on the 3-sphere S^3 (and also on Euclidean space R^3). By the geometrization of finite group actions on 3-manifolds, if such an action is smooth then it is conjugate to an…

Geometric Topology · Mathematics 2016-09-02 Bruno P. Zimmermann

We revisit the problem of isospectral spherical space forms with non-cyclic fundamental groups after the works by Ikeda, Gilkey and Wolf. We find the first pair of spherical space forms with non-isomorphic fundamental groups and the same…

Differential Geometry · Mathematics 2026-02-16 Mauro Colantonio , Emilio A. Lauret

The spectrum of a finite group is the set of orders of its elements. We are concerned with finite groups having the same spectrum as a direct product of nonabelian simple groups with abelian Sylow $2$-subgroups. For every positive integer…

Group Theory · Mathematics 2026-04-06 M. A. Grechkoseeva , A. V. Vasil'ev