2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/216257We prove two uniqueness theorems for solutions of linear and nonlinear wave equations; the first theorem is in the Minkowski space while the second is in the domain of outer communication of a Kerr black hole. Both theorems concern ill posed Cauchy problems on smooth, bifurcate, characteristic hypersurfaces. In the case of the Kerr space-time this hypersurface is the event horizon of the black hole.Various correctionsGeneral Relativity and Quantum CosmologyAnalysis of PDEstext