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We give an explicit and character-free construction of a complete set of orthogonal primitive idempotents of a rational group algebra of a finite nilpotent group and a full description of the Wedderburn decomposition of such algebras. An…

Rings and Algebras · Mathematics 2010-01-11 E. Jespers , G. Olteanu , A. del Rio

We compute the rank of the group of central units in the integral group ring $\Z G$ of a finite strongly monomial group $G$. The formula obtained is in terms of the strong Shoda pairs of $G$. Next we construct a virtual basis of the group…

Rings and Algebras · Mathematics 2013-04-25 Eric Jespers , Gabriela Olteanu , Ángel del Río , Inneke Van Gelder

We present a method to explicitly compute a complete set of orthogonal primitive idempotents in a simple component with Schur index 1 of a rational group algebra $\mathbb{Q}G$ for $G$ a finite generalized strongly monomial group. For the…

Rings and Algebras · Mathematics 2024-01-17 Gurmeet K. Bakshi , Jyoti Garg , Gabriela Olteanu

In this paper, a construction of Shoda pairs using character triples is given for a large class of monomial groups including abelian-by-supersolvable and subnormally monomial groups. The computation of primitive central idempotents and the…

Group Theory · Mathematics 2017-02-06 Gurmeet K. Bakshi , Gurleen Kaur

For the rational group algebra $\mathbb{Q}G$ of a finite group $G$, we provide an effective method to compute a complete set of matrix units and, in particular, primitive orthogonal idempotents in a simple component of $\mathbb{Q}G$, which…

Rings and Algebras · Mathematics 2024-06-17 Gurmeet Kaur Bakshi , Jyoti Garg

We describe the primitive central idempotents of the group algebra over a number field of finite monomial groups. We give also a description of the Wedderburn decomposition of the group algebra over a number field for finite strongly…

Representation Theory · Mathematics 2014-11-24 Gabriela Olteanu , Inneke Van Gelder

We develop a practical algorithm to decide whether a finitely generated subgroup of a solvable algebraic group $G$ is arithmetic. This incorporates a procedure to compute a generating set of an arithmetic subgroup of $G$. We also provide a…

Group Theory · Mathematics 2019-05-13 W. A. de Graaf , A. S. Detinko , D. L. Flannery

Let G be a unipotent algebraic subgroup of some GL_m(C) defined over Q. We describe an algorithm for finding a finite set of generators of the subgroup G(Z) = G \cap GL_m(Z). This is based on a new proof of the result (in more general form…

Group Theory · Mathematics 2008-07-01 Willem de Graaf , Andrea Pavan

We give a description of the primitive central idempotents of the rational group algebra QG of a finite group G. Such a description is already investigated by Jespers, Olteanu and del R\'io, but some unknown scalars are involved. Our…

Representation Theory · Mathematics 2013-06-25 Geoffrey Janssens

Let $\mathbb F_q$ be a finite field with $q$ elements, $G$ a finite cyclic group of order $p^k$ and $p$ is an odd prime with ${\rm gcd}(q,p)=1$. In this article, we determine an explicit expression for the primitive idempotents of $\mathbb…

Rings and Algebras · Mathematics 2014-04-28 F. E. Brochero Martínez , C. R. Giraldo Vergara

Let $G$ be a finite solvable group. Then $G$ always has a useful presentation, which we call a "long presentation". Using a "long presentation" of $G$, we present an inductive method of constructing the irreducible representations of $G$…

Representation Theory · Mathematics 2018-10-11 Ravi S. Kulkarni , Soham Swadhin Pradhan

We provide an explicit construction for a complete set of orthogonal primitive idempotents of finite group algebras over nilpotent groups. Furthermore, we give a complete set of matrix units in each simple epimorphic image of a finite group…

Representation Theory · Mathematics 2013-02-19 Inneke Van Gelder , Gabriela Olteanu

We provide algorithms for performing computations in generalized numerical semigroups, that is, submonoids of $\mathbb{N}^{d}$ with finite complement in $\mathbb{N}^{d}$. These semigroups are affine semigroups, which in particular implies…

Combinatorics · Mathematics 2019-11-22 Carmelo Cisto , Manuel Delgado , Pedro A. García-Sánchez

We call a group $G$ {\it algorithmically finite} if no algorithm can produce an infinite set of pairwise distinct elements of $G$. We construct examples of recursively presented infinite algorithmically finite groups and study their…

Group Theory · Mathematics 2010-12-09 A. Myasnikov , D. Osin

The dominant theme of this thesis is the construction of matrix representations of finite solvable groups using a suitable system of generators. For a finite solvable group $G$ of order $N = p_{1}p_{2}\dots p_{n}$, where $p_{i}$'s are…

Representation Theory · Mathematics 2018-10-10 Soham Swadhin Pradhan

The authors of [Primitive orthogonal idempotents for R-trivial monoids, Journal of Algebra] provide an algorithm for finding a complete system of primitive orthogonal idempotents for CM, where M is any finite R-trivial monoid. Their method…

Representation Theory · Mathematics 2019-06-10 Eddie Nijholt , Bob Rink , Sören Schwenker

The complex algebra of an inverse semigroup with finitely many idempotents in each $\mathcal D$-class is stably finite by a result of Munn. This can be proved fairly easily using $C^*$-algebras for inverse semigroups satisfying this…

Group Theory · Mathematics 2022-07-25 Pedro V. Silva , Benjamin Steinberg

An approach to representations of finite groups is presented without recourse to character theory. Considering the group algebra C[G] as an algebra of linear maps on C[G] (by left multiplication), we derive the primitive central idempotents…

Representation Theory · Mathematics 2008-03-31 Robin Endelman , Manash Mukherjee

We consider pairs of finitely presented, residually finite groups $P\hookrightarrow\G$ for which the induced map of profinite completions $\hat P\to \hat\G$ is an isomorphism. We prove that there is no algorithm that, given an arbitrary…

Group Theory · Mathematics 2008-10-03 Martin R. Bridson

An algorithm for the explicit computation of a complete set of primitive central idempotents, Wedderburn decomposition and the automorphism group of the semisimple group algebra of a finite metabelian group is developed. The algorithm is…

Representation Theory · Mathematics 2013-11-07 Gurmeet K. Bakshi , Shalini Gupta , Inder Bir S. Passi
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