2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/127603After attaching explicitly to the Möbius strip an invertible module over the ring of real polynomial functions on the real circle, we expound as directly as possible the many faces and the main algebraic properties of invertible modules. The goal is to make this algebraic concept accessible to a wide mathematical audience.32 pagesCommutative Algebra13C10text