Supercharacters and superclasses for algebra groups

P Diaconis, I Isaacs - Transactions of the American Mathematical Society, 2008 - ams.org
We study certain sums of irreducible characters and compatible unions of conjugacy classes
in finite algebra groups. These groups generalize the unimodular upper triangular groups …

Supercharacter theory constructions corresponding to Schur ring products

AOF Hendrickson - Communications in Algebra, 2012 - Taylor & Francis
Diaconis and Isaacs have defined the supercharacter theories of a finite group to be certain
approximations to the ordinary character theory of the group. We make explicit the …

Basic characters of the unitriangular group (for arbitrary primes)

C André - Proceedings of the American Mathematical Society, 2002 - ams.org
Let $ U_ {n}(q) $ denote the (upper) unitriangular group of degree $ n $ over the finite field
$\mathbb {F} _ {q} $ with $ q $ elements. In this paper we consider the basic (complex) …

Supercharacter formulas for pattern groups

P Diaconis, N Thiem - Transactions of the American Mathematical Society, 2009 - ams.org
C. Andre and N. Yan introduced the idea of a supercharacter theory to give a tractable
substitute for character theory in wild groups such as the unipotent uppertriangular group …

Branching rules in the ring of superclass functions of unipotent upper-triangular matrices

N Thiem - Journal of Algebraic combinatorics, 2010 - Springer
It is becoming increasingly clear that the supercharacter theory of the finite group of
unipotent upper-triangular matrices has a rich combinatorial structure built on set-partitions …

Hopf monoids from class functions on unitriangular matrices

M Aguiar, N Bergeron, N Thiem - Algebra & Number Theory, 2013 - msp.org
We build, from the collection of all groups of unitriangular matrices, Hopf monoids in Joyal's
category of species. Such structure is carried by the collection of class function spaces on …

Closed expressions for averages of set partition statistics

B Chern, P Diaconis, DM Kane… - Research in the …, 2014 - Springer
In studying the enumerative theory of super characters of the group of upper triangular
matrices over a finite field, we found that the moments (mean, variance, and higher …

A supercharacter analogue for normality

E Marberg - Journal of Algebra, 2011 - Elsevier
Diaconis and Isaacs define in [8](Diaconis and Isaacs, 2008) a supercharacter theory for
algebra groups over a finite field by constructing certain unions of conjugacy classes called …

Superinduction for pattern groups

E Marberg, N Thiem - Journal of Algebra, 2009 - Elsevier
It is well known that the representation theory of the finite group of unipotent upper-triangular
matrices Un over a finite field is a wild problem. By instead considering approximately …

Supercharacters of the adjoint group of a finite radical ring

CAM André, AP Nicolás - 2008 - degruyter.com
We study irreducible characters, and define and study supercharacters of the adjoint group
of a finite radical ring. We extend work of Halasi on irreducible characters, and recent work …