Certain subsemigroups of orthodox semigroups
Let S be an orthodox semigroup and E(S) the band of idempotents of S. The author describes (1) the least fundamental inverse congruence on S, (2) the greatest subsemigroup of S containing E(S) which is a union (band) of groups, and (3) a necessary and sufficient condition for the union of maximal subgroups of S to be a subsemigroup of S.
scientific article; zbMATH DE number 3910649