2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34936We review some basic natural geometric objects on null hypersurfaces. Gauss-Codazzi constraints are given in terms of the analog of canonical ADM momentum which is a well defined tensor density on the null surface. Bondi cones are analyzed with the help of this object.10 pagesGeneral Relativity and Quantum Cosmologytext