2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/113877A self-contained exposition is given of the topological and Galois-theoretic properties of the category of combinatorial 1-complexes, or graphs, very much in the spirit of Stallings. A number of classical, as well as some new results about free groups are derived.22 pagesGroup Theory20F04text