# nLab trivial representation

Contents

### Context

#### Representation theory

representation theory

geometric representation theory

# Contents

## Definition

A representation/action $V \times G \longrightarrow V$ is trivial if it is given by the projection out of the product onto $V$.

## Properties

###### Example

(induced representation of the trivial representation)

Let $G$ be a finite group and $H \overset{\iota}{\hookrightarrow} G$ a subgroup-inclusion. Then the induced representation in Rep(G) of the 1-dimensional trivial representation $\mathbf{1} \in Rep(H)$ is the permutation representation $k[G/H]$ of the coset G-set $G/H$:

$\mathrm{ind}_H^G\big( \mathbf{1}\big) \;\simeq\; k[G/H] \,.$

This follows directly as a special case of the general formula for induced representations of finite groups (this Example).

homotopy type theoryrepresentation theory
pointed connected context $\mathbf{B}G$∞-group $G$
dependent type on $\mathbf{B}G$$G$-∞-action/∞-representation
dependent sum along $\mathbf{B}G \to \ast$coinvariants/homotopy quotient
context extension along $\mathbf{B}G \to \ast$trivial representation
dependent product along $\mathbf{B}G \to \ast$homotopy invariants/∞-group cohomology
dependent product of internal hom along $\mathbf{B}G \to \ast$equivariant cohomology
dependent sum along $\mathbf{B}G \to \mathbf{B}H$induced representation
context extension along $\mathbf{B}G \to \mathbf{B}H$restricted representation
dependent product along $\mathbf{B}G \to \mathbf{B}H$coinduced representation
spectrum object in context $\mathbf{B}G$spectrum with G-action (naive G-spectrum)

Last revised on January 28, 2019 at 05:02:59. See the history of this page for a list of all contributions to it.