I have a question relating to p109 of Local representation theory by JL Alperin.
Let $G$ be a finite group and let $N$ be a normal subgroup. If $B$ is a block of $G$, why must $B$ be a summand of $(k_{N\times N})^{G\times G}$?
I have a question relating to p109 of Local representation theory by JL Alperin.
Let $G$ be a finite group and let $N$ be a normal subgroup. If $B$ is a block of $G$, why must $B$ be a summand of $(k_{N\times N})^{G\times G}$?