scholarly journals On complete reducibility of tensor products of simple modules over simple algebraic groups

2021 ◽  
Vol 8 (8) ◽  
pp. 249-276
Author(s):  
Jonathan Gruber
Keyword(s):  
Algebraic Groups ◽  
Tensor Products ◽  
Simple Modules ◽  
Complete Reducibility

scholarly journals Some Remarks on Branching Rules and Tensor Products for Algebraic Groups

1999 ◽  
Vol 217 (1) ◽  
pp. 335-351 ◽  
Author(s):  
Jonathan Brundan ◽  
Alexander Kleshchev
Keyword(s):  
Algebraic Groups ◽  
Tensor Products ◽  
Branching Rules

scholarly journals On Extensions of Simple Modules over Symmetric and Algebraic Groups

2001 ◽  
Vol 238 (2) ◽  
pp. 843-844 ◽  
Author(s):  
A.S.Kleshchev and J. Sheth
Keyword(s):  
Algebraic Groups ◽  
Simple Modules

scholarly journals ON RELATIVE COMPLETE REDUCIBILITY

2020 ◽  
Vol 71 (1) ◽  
pp. 321-334 ◽  
Author(s):  
Christopher Attenborough ◽  
Michael Bate ◽  
Maike Gruchot ◽  
Alastair Litterick ◽  
Gerhard Röhrle
Keyword(s):  
Lie Algebras ◽  
Algebraic Groups ◽  
Reductive Group ◽  
Natural Generalization ◽  
Conjugacy Classes ◽  
Closed Field ◽  
Complete Reducibility ◽  
Algebraic Description ◽  
Reductive Subgroup

Abstract Let $K$ be a reductive subgroup of a reductive group $G$ over an algebraically closed field $k$. The notion of relative complete reducibility, introduced in [M. Bate, B. Martin, G. Röhrle, R. Tange, Complete reducibility and conjugacy classes of tuples in algebraic groups and Lie algebras, Math. Z.269 (2011), no. 1, 809–832], gives a purely algebraic description of the closed $K$-orbits in $G^n$, where $K$ acts by simultaneous conjugation on $n$-tuples of elements from $G$. This extends work of Richardson and is also a natural generalization of Serre’s notion of $G$-complete reducibility. In this paper we revisit this idea, giving a characterization of relative $G$-complete reducibility, which directly generalizes equivalent formulations of $G$-complete reducibility. If the ambient group $G$ is a general linear group, this characterization yields representation-theoretic criteria. Along the way, we extend and generalize several results from [M. Bate, B. Martin, G. Röhrle, R. Tange, Complete reducibility and conjugacy classes of tuples in algebraic groups and Lie algebras, Math. Z.269 (2011), no. 1, 809–832].

scholarly journals A note on vertices of indecomposable tensor products

2020 ◽  
Vol 23 (3) ◽  
pp. 385-391
Author(s):  
Markus Linckelmann
Keyword(s):  
Finite Group ◽  
Group Algebra ◽  
Present Note ◽  
Tensor Products ◽  
Solvable Groups ◽  
Sufficient Criterion ◽  
Indecomposable Modules ◽  
Main Motivation ◽  
Simple Modules ◽  
A Finite Group

AbstractG. Navarro raised the question of when two vertices of two indecomposable modules over a finite group algebra generate a Sylow p-subgroup. The present note provides a sufficient criterion for this to happen. This generalises a result by Navarro for simple modules over finite p-solvable groups, which is the main motivation for this note.

Truncated symmetric powers and modular representations of GLn

1996 ◽  
Vol 119 (2) ◽  
pp. 231-242 ◽  
Author(s):  
Stephen Doty ◽  
Grant Walker
Keyword(s):  
General Linear Group ◽  
Schur Functions ◽  
Tensor Products ◽  
Modular Representation ◽  
Modular Representations ◽  
Modular Representation Theory ◽  
Simple Modules ◽  
Symmetric Powers ◽  
Natural Module ◽  
Natural Way

AbstractSeveral results are obtained relating to the modular representation theory of the general linear group GLn in the defining characteristic p > 0. In Section 1, embeddings of certain simple modules in symmetric powers of the natural module, or in tensor products of truncated symmetric powers, are constructed. In Section 2, cases are found where simple quotientsof Schur modules H0(λ) can be constructed by extending theidea of truncation to these modules in a natural way. In Section 3, the characters of those simple modules which can be constructed as twisted tensor products of truncated symmetric powers are expressed in terms of Schur functions.

scholarly journals Semisimplification for subgroups of reductive algebraic groups

2020 ◽  
Vol 8 ◽  
Author(s):  
Michael Bate ◽  
Benjamin Martin ◽  
Gerhard Röhrle
Keyword(s):  
Algebraic Group ◽  
Invariant Theory ◽  
Algebraic Groups ◽  
Geometric Invariant ◽  
Reductive Algebraic Group ◽  
Complete Reducibility ◽  
Special Cases ◽  
Closed Fields ◽  
Completely Reducible ◽  
Algebraically Closed Fields

Let G be a reductive algebraic group—possibly non-connected—over a field k, and let H be a subgroup of G. If $G= {GL }_n$ , then there is a degeneration process for obtaining from H a completely reducible subgroup $H'$ of G; one takes a limit of H along a cocharacter of G in an appropriate sense. We generalise this idea to arbitrary reductive G using the notion of G-complete reducibility and results from geometric invariant theory over non-algebraically closed fields due to the authors and Herpel. Our construction produces a G-completely reducible subgroup $H'$ of G, unique up to $G(k)$ -conjugacy, which we call a k-semisimplification of H. This gives a single unifying construction that extends various special cases in the literature (in particular, it agrees with the usual notion for $G= GL _n$ and with Serre’s ‘G-analogue’ of semisimplification for subgroups of $G(k)$ from [19]). We also show that under some extra hypotheses, one can pick $H'$ in a more canonical way using the Tits Centre Conjecture for spherical buildings and/or the theory of optimal destabilising cocharacters introduced by Hesselink, Kempf, and Rousseau.

scholarly journals MODULES OVER QUANTUM LAURENT POLYNOMIALS

2011 ◽  
Vol 91 (3) ◽  
pp. 323-341 ◽  
Author(s):  
ASHISH GUPTA
Keyword(s):  
Tensor Product ◽  
Tensor Products ◽  
Laurent Polynomials ◽  
Base Field ◽  
Simple Modules ◽  
Holonomic Modules ◽  
Kirillov Dimension

AbstractWe show that the Gelfand–Kirillov dimension for modules over quantum Laurent polynomials is additive with respect to tensor products over the base field. We determine the Brookes–Groves invariant associated with a tensor product of modules. We study strongly holonomic modules and show that there are nonholonomic simple modules.

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