2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/76795Goursat showed that in the presence of an intermediate integral, the problem of solving a second-order Monge-Ampere equation can be reduced to solving a first-order equation, in the sense that the generic solution of the first-order equation will also be a solution of the original equation. An attempt by Hermann to give a rigorous proof of this fact contains an error; we show that there exists an essentially unique counterexample to Hermann's assertion and state and prove a correct theorem.5 pagesAnalysis of PDEsDifferential Geometry35A30 (Primary); 58A15 (Secondary)text