Preprint MA 50/2005

Local Analytic Solutions of the Generalized Dhombres Functional Equation I

Ludwig Reich, Jaroslav Smital and Marta Stefankova

We study local analytic solutions $f$ of the generalized Dhombres equation $f(xf(x))=\varphi(f(x))$ with $f(0)=0$ in the complex domain. We give an existence result, describe the structure of the set of all local analytic solutions and solve the converse problem, i.e., we characterize those local analytic functions which are solutions of a generalized Dhombres equation. Connections of generalized Dhombers equations with linear functional equations and generalized B\"ottcher equations are used. Furthermore, we establish relations of generalized Dhombres equations with Briont-Bouquet differential equations and with iteration groups. Finally, as an application of B\"ottcher functions, we describe the connections between two generalized Dhombres equations and the representations of their solutions as infinite products.

Mathematics Subject Classification. Primary 30D05, 34M25, 39B12, 39B32; Secondary 30B10.