Blocks

Unless stated otherwise, blocks of a finite group [math]G[/math] will be indecomposable two-sided ideals of [math]kG[/math]. In some situations it will be the corresponding block of [math]\mathcal{O}G[/math].

[math]B_0(A)[/math] will denote the principal block of an algebra [math]A[/math]. However we often use the notation of GAP to label blocks of certain groups, where the principal block is usually labelled [math]B_1(kG)[/math].