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Let $G$ be a group with a finite subgroup $H$. We define the $L^2$-multiplicity of an irreducible representation of $H$ in the $L^2$-homology of a proper $G$-CW-complex. These invariants generalize the $L^2$-Betti numbers. Our main results…

Group Theory · Mathematics 2020-03-25 Steffen Kionke

Let G be an almost simple, simply connected algebraic group over an algebraically closed field of characteristic p>0. In this paper we restate our conjecture from 1979 on the characters of irreducible modular representations of G so that it…

Representation Theory · Mathematics 2014-08-19 G. Lusztig

Let G be the real points of a simply connected, semisimple, simply laced complex Lie group, and let \tilde{G} be the nonlinear double cover of G. We discuss a set of small genuine irreducible representations of \tilde{G} which can be…

Representation Theory · Mathematics 2017-08-01 Wan-Yu Tsai

Let $G$ be a finite group and $p$ be a prime divisor of $|G|$. An irreducible $p$-Brauer character $\varphi$ of $G$ is called super-monomial if every primitive $p$-Brauer character inducing $\varphi$ is linear. The group $G$ is said to be a…

Group Theory · Mathematics 2026-02-10 Xiaoyou Chen , A. R. Moghaddamfar

The purpose of the present paper is to investigate a hypergroup arising from irreducible characters of a compact group G and a closed subgroup of G with finite index. The convolution of this hypergroup is introduced by inducing irreducible…

Representation Theory · Mathematics 2016-05-13 Hebert Heyer , Satoshi Kawakami , Tatsuya Tsurii , Satoe Yamanaka

We present a description of non-solvable groups in which all real irreducible character degrees are prime-power numbers.

Group Theory · Mathematics 2021-07-02 Lorenzo Bonazzi

Navarro defined the set ${Irr}(G \mid Q, \delta) \subseteq {Irr}(G)$, where $Q$ is a $p$-subgroup of a $p$-solvable group $G$, and shows that if $\delta$ is the trivial character of $Q$, then ${Irr}(G \mid Q, \delta)$ provides a set of…

Group Theory · Mathematics 2007-05-23 James P. Cossey

A new conjecture on characters of finite groups, related to the McKay conjecture, was proposed recently by the first and third authors. In this paper, we prove it for $p$-solvable groups when $p$ is odd.

Representation Theory · Mathematics 2025-06-16 Alexander Moretó , Gabriel Navarro , Noelia Rizo

Let $G$ be a finite group, and write ${\rm cd}(G)$ for the degree set of the complex irreducible characters of $G$. The group $G$ is said to satisfy the {\it two-prime hypothesis} if, for any distinct degrees $a, b \in {\rm cd}(G)$, the…

Group Theory · Mathematics 2017-01-20 Mark L. Lewis , Yanjun Liu , Hung P. Tong-Viet

The concept of a supercharacter theory of a finite group was introduced by Diaconis and Isaacs as an alternative to the usual irreducible character theory, and exemplified with a particular construction in the case of finite algebra groups.…

Representation Theory · Mathematics 2021-01-28 Carlos A. M. André , Jocelyn Lochon

We show that if the principal p-block of a finite group G contains exactly 5 irreducible ordinary characters, then a Sylow p-subgroup of G has order 5, 7 or is isomorphic to one of the non-abelian 2-groups of order 8.

Group Theory · Mathematics 2021-05-07 Noelia Rizo , Amanda Schaeffer Fry , Carolina Vallejo

Let $\mathbb{F}_q$ be a finite field with $q$ elements, where $q$ is the power of an odd prime, and let $\mathrm{GSp}(2n, \mathbb{F}_q)$ and $\mathrm{GO}^{\pm}(2n, \mathbb{F}_q)$ denote the symplectic and orthogonal groups of similitudes…

Representation Theory · Mathematics 2009-08-18 C. Ryan Vinroot

In this paper, we compute the conjugacy classes and the list of irreducible characters of GSp(4,q), where q is odd. We also determine precisely which irreducible characters are non-cuspidal and which are generic. These characters are then…

Representation Theory · Mathematics 2016-04-26 Jeffery Breeding

Slattery has generalized Brauer's theory of p-blocks of finite groups to pi-blocks of pi-separable groups where pi is a set of primes. In this setting we show that the order of a defect group of a pi-block B is bounded in terms of the…

Representation Theory · Mathematics 2018-10-16 Benjamin Sambale

Let $G = {\rm U}(2m, {\mathbb F}_{q^2})$ be the finite unitary group, with $q$ the power of an odd prime $p$. We prove that the number of irreducible complex characters of $G$ with degree not divisible by $p$ and with Frobenius-Schur…

Representation Theory · Mathematics 2009-04-14 C. Ryan Vinroot

The theory of differential characters is developed completely from a de Rham - Federer viewpoint. Characters are defined as equivalence classes of special currents, called sparks, which appear naturally in the theory of singular…

Differential Geometry · Mathematics 2018-02-22 F. Reese Harvey , H. Blaine Lawson, , John Zweck

Let $G$ be a finite group and \( M \) be a maximal subgroup of \( G \). We call every irreducible constituent \( \chi \) of \( (1_M)^G \) a \( \mathcal{P} \)-character of \( G \) with respect to \( M \). In this paper, we prove that all…

Group Theory · Mathematics 2026-03-31 Jiakuan Lu , hangyang Meng

Let $d$ be a positive integer. We study the proportion of irreducible characters of infinite families of irreducible Coxeter groups whose values evaluated on a fixed element $g$ are divisible by $d$. For Coxeter groups of types $A_n, B_n$…

Representation Theory · Mathematics 2025-04-29 Jyotirmoy Ganguly , Rohit Joshi

In the theory of unitary group representations, a group is called type I if all factor representations are of type I, and by a celebrated theorem of James Glimm [Gli61b], the type I groups are precisely those groups for which the…

Group Theory · Mathematics 2019-04-18 Fabio Elio Tonti , Asger Törnquist

Let $S$ be a Suzuki group $^2B_2(q^2)$, where $q^2=2^{2f+1}$, $f\geqslant 1$. In this paper, we determine the degrees of the ordinary complex irreducible characters of every group $G$ such that $S\leqslant G\leqslant \Aut(S)$.

Group Theory · Mathematics 2016-08-04 Mehdi Ghaffarzadeh