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We give new, explicit and asymptotically sharp, lower bounds for dimensions of irreducible modular representations of finite symmetric groups.

Representation Theory · Mathematics 2019-09-10 Alexander Kleshchev , Lucia Morotti , Pham Huu Tiep

Basic modules of McLain groups $M=M(\Lambda,\leq, R)$ are defined and investigated. These are (possibly infinite dimensional) analogues of Andr\'e's supercharacters of $U_n(q)$. The ring $R$ need not be finite or commutative and the field…

Representation Theory · Mathematics 2016-11-01 Fernando Szechtman , Allen Herman , Mohammad Izadi

All irreducible representations of the Chinese monoid $C_n$, of any rank $n$, over a nondenumerable algebraically closed field $K$, are constructed. It turns out that they have a remarkably simple form and they can be built inductively from…

Representation Theory · Mathematics 2016-01-05 Łukasz Kubat , Jan Okniński

We give a simple formula for the essential dimension of a finite pseudo-reflection group at a prime p and determine the absolute essential dimension for most irreducible pseudo-reflection groups. We also study the "poor man's essential…

Algebraic Geometry · Mathematics 2015-06-12 Alexander Duncan , Zinovy Reichstein

In our previous paper, we gave a complete list of the finite non-abelian simple groups whose holomorph contains a solvable regular subgroup. In this paper, we refine our previous work by considering all finite almost simple groups. In…

Group Theory · Mathematics 2024-03-25 Cindy Tsang

Let R be a commutative ring with identity and M be an R-module. In this paper, we will introduce the concept of 2-irreducible (resp., strongly 2- irreducible) submodules of M as a generalization of irreducible (resp., strongly irreducible)…

Commutative Algebra · Mathematics 2019-05-27 Faranak Farshadifar , Habibollah Ansari-Toroghy

This article gives the structure of all projective indecomposable modules in blocks with non-cyclic defect group for $n\leq 11$, and almost all in the case of $n=12$, leaving four simple modules for $p=2$ and one simple module for $p=3$.

Representation Theory · Mathematics 2016-05-18 David A. Craven

Let $K$ be an algebraically closed field of characteristic $p\geqslant 0$ and let $Y=\mbox{Spin}_{2n+1}(K)$ $(n\geqslant 3)$ be a simply connected simple algebraic group of type $B_n$ over $K.$ Also let $X$ be the subgroup of type $D_n,$…

Representation Theory · Mathematics 2016-08-23 Mikaël Cavallin

We consider a bipartite distance-regular graph $G$ with diameter at least 4 and valency at least 3. Fix a vertex of $G$ and let $T$ denote the corresponding subconstituent algebra. We give a detailed description of a certain type of…

Combinatorics · Mathematics 2007-05-23 Mark MacLean , Paul Terwilliger

We give a short proof of the fact that if all characteristic p simple modules of the finite group G have dimension less than p, then G has a normal Sylow p-subgroup.

Group Theory · Mathematics 2021-02-09 Geoffrey R. Robinson

The group is interesting as the first example of split rank 2 semisimple group, all the irreducible unitary representations of which are known. We make a precise realization of the discrete series representations (in Section 2) by using the…

Quantum Algebra · Mathematics 2016-05-17 Do Ngoc Diep , Do Thi Phuong Quynh

A method to construct irreducible unitary representations of a hyperspecial compact subgroup of a reductive group over p-adic field with odd p is presented. Our method is based upon Cliffods theory and Weil representations over finite…

Group Theory · Mathematics 2018-05-17 Koichi Takase

Given an initial family of sets, we may take unions, intersections and complements of the sets contained in this family in order to form a new collection of sets; our construction process is done recursively until we obtain the last family.…

Combinatorics · Mathematics 2024-09-11 Jorge Garcia , Rosemarie Bongers , Jonathan Detgen , Walter Morales

The category ${\rm CM}(B_{k,n}) $ of Cohen-Macaulay modules over a quotient $B_{k,n}$ of a preprojective algebra provides a categorification of the cluster algebra structure on the coordinate ring of the Grassmannian variety of…

Representation Theory · Mathematics 2021-03-23 Karin Baur , Dusko Bogdanic , Jian-Rong Li

We construct the first examples of what we call fake ES-irreducible components; Definition 2.8. In our way to do so, we classify the automorphism groups of smooth plane sextics that only have automorphisms of order 3 or less; Theorems 2.1,…

Algebraic Geometry · Mathematics 2023-09-19 Eslam Badr , Francesc Bars

We determine the structure of the semisimple group algebra of certain groups over the rationals and over those finite fields where the Wedderburn decompositions have the least number of simple components. We apply our work to obtain similar…

Representation Theory · Mathematics 2010-09-06 Raul A. Ferraz , Edgar G. Goodaire , Cesar Polcino Milies

We construct the irreducible unipotent modules of the finite general linear groups using tableaux. Our construction is analogous to that of James (1976) for the symmetric groups, answering an open question as to whether such a construction…

Representation Theory · Mathematics 2018-02-20 Scott Andrews

We introduce 3-irreducible modules, even roots and odd roots for Leibniz algebras, produce a basis for a root space of a Leibniz algebra with a semisimple Lie factor, and classify finite dimensional simple Leibniz algebras with Lie factor…

Rings and Algebras · Mathematics 2007-05-23 Keqin Liu

There exist irreducible exact covering systems (ECS). These are ECS which are not a proper split of a coarser ECS. However, an ECS admiting a maximal modulus which is divisible by at most two distinct primes, primely splits a coarser ECS.…

Combinatorics · Mathematics 2015-06-03 Ofir Schnabel

Let G be a semisimple group over an algebraically closed field of characteristic p>0. We give a (partly conjectural) simple, closed formula for the character of many indecomposable tilting rational G-modules, assuming that p is large.

Representation Theory · Mathematics 2015-02-18 George Lusztig , Geordie Williamson