Gilbert Baumslag, B.H. Neumann, Hanna Neumann, and Peter M. Neumann successfully exploited their concept of discrimination to obtain generating groups of product varieties via the wreath product construction. We have discovered this same underlying concept in a somewhat different context. Specifically, let V be a non-trivial variety of algebras. For each cardinal α let Fα(V) be a V-free algebra of rank α. Then for a fixed cardinal r one has the equivalence of the following two statements ...
Gaglione, A.M. & Spellman, D. (1987). The persistence of universal formulae in free algebras. Bulletin of the Australian Mathematical Society, 36(1), 11-17. doi: 10.1017/S0004972700026253