A note on commutators in compact semisimple Lie algebras

Abstract

Given two elements $A,B$ in a compact semisimple Lie algebra, we show that there is a regular element $X$ and elements $Y,Z$ with $A=[X,Y]$ and $B=[X,Z]$. In the course of the proof we show also that every linear subspace $V$ of codimension at most 2 in the Lie algebra contains a CSA.