Restrictive Semigroups of Closed Functions

Abstract

It is assumed that all topological spaces discussed in this paper are T1 spaces. A function ƒ mapping a topological space X into itself is a closed function if ƒ[H] is closed for each closed subset H of S. The semigroup, under composition, of all closed functions mapping X into X is denoted by Γ(X). These were among the semigroups under consideration in (4).