GROUPOID SYMMETRY AND CONSTRAINTS IN GENERAL RELATIVITY
GROUPOID SYMMETRY AND CONSTRAINTS IN GENERAL RELATIVITY
When the vacuum Einstein equations are cast in the form of hamiltonian evolution equations, the initial data lie in the cotangent bundle of the manifold M\Sigma\ of riemannian metrics on a Cauchy hypersurface \Sigma. As in every lagrangian field theory with symmetries, the initial data must satisfy constraints. But, unlike …