Left (Right) Regular Elements of Some Transformation Semigroups

For a nonempty set X, let T(X) be the total transformation semigroup on X. In this paper, we consider subsemigroups of which are defined by T(X,Y) ={α∈T(X):Xα⊆Y}andS(X,Y)={α∈T(X):Yα⊆Y} where Y is non-empty subset We characterize left regular and right elements both S(X,Y). Moreover, necessary sufficient conditions for S(X,Y) to given. These results then applied determine numbers in finite