Subordination problems for certain meromorphic functions

Let ? be the class of meromorphic functions f of the form f(z) = 1/z + a0 + a1z + · · · that are analytic in the punctured disk U0. For f ? ?, operators Dnf with n ? Z = {…,?1, 0, 1,…} are introduced. Applying differential subordinations for analytic functions in the open unit disc U, some interesting properties of f ? ? with Dnf are discussed, and argument problems of Dnf are given. Also, we consider some simple problems for our results.