Suppose we have a representation of $G$. Given a $G$-invariant subspace $W$ we can define another representation (subrepresentation) by means of restrictions
$$ \rho: G \to GL(W). $$Observe that $V$ itself and $\{0\}$ are trivial subrepresentations.
The absence of non-trivial representation is called irreducibility.
________________________________________
________________________________________
________________________________________
Author of the notes: Antonio J. Pan-Collantes
INDEX: