Cartan solvability criterion (source code)

= Cartan solvability criterion
{c}
{wiki=Cartan's_criterion}

A complex Lie subalgebra $\mathfrak h\subseteq\mathfrak{gl}(V)$ is solvable if
$$
\operatorname{tr}(xy)=0
$$
for every $x\in[\mathfrak h,\mathfrak h]$ and $y\in\mathfrak h$. For an abstract Lie algebra, this is equivalent to $\kappa(\mathfrak h,[\mathfrak h,\mathfrak h])=0$.