Constraint-free theories of gravitation

Lovelock actions (more precisely, extended Gauss-Bonnet forms) when varied as Cartan forms on subspaces of higher-dimensional flat Riemannian manifolds, generate well set, causal exterior differential systems. In particular, the Einstein-Hilbert action 4-form, varied on a four-dimensional subspace of E-10, yields a well set generalized theory of gravity having no constraints. Ricci-flat solutions are selected by initial conditions on a bounding 3-space.