2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/115153We show that, for a closed non-orientable surface $F$, an automorphism of $H_1(F,\Z)$ is induced by a homeomorphism of $F$ if and only if it preserves the (mod 2) intersection pairing. We shall also prove the corresponding result for punctured surfaces.General Topology57N05text