“…The group ν(G) inherits many properties of the argument G; for instance, if G is a finite π−group (π a set o primes), nilpotent, solvable, polycyclic-by-finite, or a locally finite group, then so is ν(G) (and hence also G ⊗ G and G ∧ G) [15,3,8,1,9]. For a deeper discussion of commutator approach we refer the reader to [7,10].…”