Engel groups with an identity

Abstract

We give an affirmative answer to the question whether a residually finite Engel group satisfying an identity is locally nilpotent. More generally, for a residually finite group [Formula: see text] with an identity, we prove that the set of right Engel elements of [Formula: see text] is contained in the Hirsch–Plotkin radical of [Formula: see text]. Given an arbitrary word [Formula: see text], we also show that the class of all groups [Formula: see text] in which the [Formula: see text]-values are right [Formula: see text]-Engel and [Formula: see text] is locally nilpotent is a variety.