  Motivated by numerical integration on manifolds, we relate the algebraic
properties of invariant connections to their geometric properties. Using this
perspective, we generalize some classical results of Cartan and Nomizu to
invariant connections on algebroids. This has fundamental consequences for the
theory of numerical integrators, giving a characterization of the spaces on
which Butcher and Lie-Butcher series methods, which generalize Runge-Kutta
methods, may be applied.
