2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/123783We consider the question of when the dual of a Whitehead group is a test group for Whitehead groups. This turns out to be equivalent to the question of when the tensor product of two Whitehead groups is Whitehead. We investigate what happens in different models of set theory.LogicGroup Theorytext