2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/137330We study the action of the group Aut(F_n) of automorphisms of a finitely generated free group on the degree 2 subcomplex of the spine of Auter space. Hatcher and Vogtmann showed that this subcomplex is simply connected, and we use the method described by K. S. Brown to deduce a new presentation of Aut(F_n).Missing relation added. Final version to appear in Journal of Group TheoryGroup Theory20F05; 20F28text