$ S $-unit values of $ G_n + G_m $ in function fields

Abstract

In this paper we consider a simple linear recurrence sequence $ G_n $ defined over a function field in one variable over the field of complex numbers. We prove an upper bound on the indices $ n $ and $ m $ such that $ G_n + G_m $ is an $ S $-unit. This is a function field analogue of already known results in number fields.