Semigroups generated by certain operators on varieties of completely regular semigroups (Q1079668)

The operators \(C,K,L,T,T_{\ell}\) and \(T_ r\) on the lattice \({\mathcal L}({\mathcal C}{\mathcal R})\) of varieties of completely regular semigroups have played an important role in recent studies of \({\mathcal L}({\mathcal C}{\mathcal R})\). Although each of these operators is idempotent, when applied in various combinations to the trivial variety they yield varieties for which the only upper bound is \({\mathcal C}{\mathcal R}\). The semigroups generated by various subsets of \(\{C,K,L.T,T_ r,T_{\ell}\}\) are determined here in terms of generators and relations.