Bi-invariant Riemannian metric
= Bi-invariant Riemannian metric
A <Riemannian metric> on a <Lie group> is bi-invariant if both left and right translations are isometries. Its identity inner product is invariant under the <Adjoint representation of a Lie group>; infinitesimally,
$$
\langle[X,Y],Z\rangle+\langle Y,[X,Z]\rangle=0.
$$
This skew-adjointness is the key additional property beyond left invariance.