2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/69495The invariance of the Welschinger numbers for real unnodal Del Pezzo surfaces, which we used for the enumeration of real rational curves on real toric Del Pezzo surfaces (see math.AG/0303378 and IMRN 49 (2003), 2639-2653), follows from J.-Y. Welschinger's theorem stated and proved in a symplectic setting (math.AG/0303145 and CRAS, Ser. I, 336 (2003), 341-344). Here, we give an algebraic geometry version of the proof of the above invariance.12 pages, no figures, minor linguistic modificationsAlgebraic Geometry14H20; 14P05; 14N10text