Completely reducible linear representation: Difference between revisions

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==Non-examples==
==Non-examples==


<math>(\Z, +)</math> has representations that are not completely reducible - for example <math>\rho</math> such that <math>\rho(N)=\begin{pmatrix}
<math>(\Z, +)</math> has representations that are not completely reducible - for example the representation <math>\rho</math> such that <math>\rho(N)=\begin{pmatrix}
1 & N\\
1 & N\\
0 & 1
0 & 1
\end{pmatrix}</math> can be shown to be a representation which is not completely reducible.
\end{pmatrix}</math> for <math>N \in \mathbb{Z}</math> can be shown to be a representation which is not completely reducible.


==Relation with other properties==
==Relation with other properties==

Revision as of 13:07, 23 October 2023

This article describes a property to be evaluated for a linear representation of a group, i.e. a homomorphism from the group to the general linear group of a vector space over a field


This article gives a basic definition in the following area: linear representation theory
View other basic definitions in linear representation theory |View terms related to linear representation theory |View facts related to linear representation theory

Definition

Symbol-free definition

A linear representation of a group is said to be completely reducible if it can be expressed as a direct sum of irreducible linear representations.

Examples

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Non-examples

has representations that are not completely reducible - for example the representation such that for can be shown to be a representation which is not completely reducible.

Relation with other properties

Stronger properties