The lattice of congruences on an inverse semigroup
David Geoffrey Green · Pacific Journal of Mathematics · 1975
The symmetry between four congruences which have figured in the literature on inverse semigroups is discussed in terms of kernels and restrictions to idempotents (kernel meaning the set of elements equivalent to idempotents).A characterization of arbitrary inverse semigroup congruences is developed from this symmetry.16. H. E. Scheiblich, Concerning congruences on symmetric inverse semigroups, Czech.