2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/60243An infinite linearly ordered set (S,<=) is called doubly homogeneous if its automorphism group A(S) acts 2-transitively on it. We show that any group G arises as outer automorphism group G cong Out(A(S)) of the automorphism group A(S), for some doubly homogeneous chain (S,<=).Group TheoryLogictext