2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/119279For large classes of systems of polynomial nonlinear PDEs necessary and sufficient conditions are given for the existence of solutions which are discontinuous across hyper-surfaces. These PDEs contain the Navier-Stokes equations, as well as those of General Relativity and Magneto-Hydrodynamics.General Mathematicstext