Derivation of a Lie algebra (source code)

= Derivation of a Lie algebra
{title2=$D[x,y]=[Dx,y]+[x,Dy]$}

= Derivations of a Lie algebra
{synonym}

A derivation of a <Lie algebra> is an <algebraic derivation>, namely a <linear map> $D:L\to L$ satisfying
$$
D[x,y]=[Dx,y]+[x,Dy].
$$
Every adjoint map $\operatorname{ad}z:x\mapsto[z,x]$ is a derivation.