Congruences on regular and completely regular semigroups
Peter G. Trotter · Journal of the Australian Mathematical Society Series A Pure Mathematics and Statistics · 1982
Abstract Congruences on regular semigroups have been characterized in terms of normal equivalences on sets of idempotents and kernels of congruences. A revised characterization is presented here with considerably simplified expressions for the least and greatest congruences associated with normal equivalences and with a new description of kernels. The results are then applied to characterize congruences on completely regular semigroups.