Notes for AKT-091001-2/0:28:08

A metric of a Lie-algebra is a nondegenerate symmetric bilinear form $<\cdot ,\cdot >:{\mathcal {G}}\otimes {\mathcal {G}}\rightarrow \mathbb {Q}$ s.t. $<[z,x],y>+<x,[z,y]>=0$