A note on the structure of graded Lie algebras

Abstract: Consider a finite-dimensional, complex Lie algebra G and a semi-simple automorphism {\alpha}. This note aims to give a short and simple proof for explicit upper bounds for the derived length of the radical R and the rank of a Levi complement G/R in terms of the number of eigenvalues of {\alpha} and the dimension of the space of fixed-points. This is an extension of classical theorems by Kreknin, Shalev and Jacobson.