Abstract
A radical class R of rings is elementary if it contains precisely
those rings whose singly generated subrings are in R. Many examples of ele-
mentary radical classes are presented, and all those which are either contained
in the Jacobson radical class or disjoint from it are described. Attention is
given to those elementary radical classes which are denable by composition
subsemigroups of the free ring on one generator. Whether every elementary
radical class is of this form remains an open question.