Note on operations generating the group operations in nilpotent groups of class 3

Abstract

Let K be a class of groups and let ω(K) denote the set of all such words w(x, y) that the group operations 1, x-1, xy in every group G ∈ K can be expressed as a superposition of w and the projections e1(x, y) = x, e2(x, y) = y.