On permutability of periodic entire functions
Using some earlier results of the reviewer, the author proves a number of results on permutable functions. For example he proves: Let F(z) and G(z) both be entire functions of order less than \(\frac12\) and let H(z) be entire. If H(z) is permutable with \(F(e^ z)+G(e^{-z})\), then H(z) has the form \[ H(z)=(k/s)z+E(z), \] where both s \((>0)\) and k are integers and E(z) is periodic with period \(2s\pi i\).
scientific article; zbMATH DE number 4099637