2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/159115We show that for any semilinear partial differential equation of order m, the infinitesimals of the independent variables depend only on the independent variables and, if m>1 and the equation is also linear in its derivatives of order m-1 of the dependent variable, then the infinitesimal of the dependent variable is at most linear on the dependent variable. Many examples of important partial differential equations in Analysis, Geometry and Mathematical - Physics are given in order to enlighten the main result.15 pages, submittedAnalysis of PDEs35H10, 58J70text