# Blocks

Unless stated otherwise, blocks of a finite group $G$ will be indecomposable two-sided ideals of $kG$. In some situations it will be the corresponding block of $\mathcal{O}G$.
$B_0(A)$ will denote the principal block of an algebra $A$. However we often use the notation of GAP to label blocks of certain groups, where the principal block is usually labelled $B_1(kG)$.