Résume | The Lie bracket of a Lie algebra $L$ induces a linear map $L \wedge L \rightarrow L$. When can the kernel of this map be generated by vectors of the form $x \wedge y$ with $[x,y]=0$? This seemingly elementary question does not seem to be tractable by elementary methods. For semisimple Lie algebras over the complex numbers Kostant has given a positive answer by means of representation theory. I will explain why a number theorist is interested in this question over fields of positive characteristics. I will sketch a solution for the Chevalley form of any split semisimple Lie algebra (joint work with O. Venjakob). |