Cauchy type functional equations related to some associative rational functions

L. Losonczi [4] determined local solutions of the generalized Cauchy equation f(F (x, y)) = f(x) + f(y) on components of the definition of a given associative rational function F. The class of the associative rational function was described by A. Chéritat [1] and his work was followed by paper [3] of the author. The aim of the present paper is to describe local solutions of the equation considered for some singular associative rational functions.