“…Similar results hold for simple Lie algebras [27], simple Jordan algebras [
17], simple nonassociative algebras [
30], and, finally, this was proved in the very general setting of finite‐dimensional simple
‐algebras [
6]. The same problem has been tackled also for
‐graded algebras of upper block triangular matrices [
5, 13, 14]. Here, we consider the case where the diagonal blocks are simple graded and
is a finite abelian group.…”