On one filtration of holomorphic functions

Abstract

In this work we consider a family of function classes constructed by means of the Gauss hypergeometric function $_2F_1(1,1;2;z) =-\frac{\log(1-z)}{z}$. We demonstrate that this family, in fact, constitutes classes of analytic functions subject to prescribed constraints on their derivatives. For these classes we obtain some geometric characteristics, including sharp coefficient estimates. Moreover, we show that this family naturally provides a filtration of infinitesimal generators, and investigate the corresponding dynamical behavior of the associated semigroups. It is interesting that this filtration links to the Ma--Minda starlike functions.