Some subsemigroups of the full transformation semigroups
Chaiwat Namnak*, Ekkachai Laysirikul
ABSTRACT: A nonempty subset T of a semigroup S is called a subsemigroup of S if T2⊆T, that is, xy∈T for all x,y∈T. For a nonempty set X, let T(X) be the semigroup of the full transformations on X, which consists of all functions from X into X with composition as the semigroup operation. The purpose of this paper is to define various subsemigroups of T(X). Necessary and sufficient conditions are given for these subsemigroups of T(X) to be equal.