The Subsemigroups Of Finite Singular Orientation-Preserving Transformation Semigroups

In this paper, We completely obtain the structures and classifications of the maximal regular subsemigroups, the maximal idempotent-generated subsemigroups and the maximal idempot -ent-generated regular subsemigroups of SOPn, consisting of all singular oriention-preserving trans -formations on a finite chain with n element. We also show that the subsemigroupis idempotent-generated.