Abstract
In this paper we study the functional equation
where a i , b i , c i are fixed complex numbers and \({f \colon \mathbb{C} \to \mathbb{C}}\) is the unknown function. We show, that if there is i such that \({b_i / c_i \neq b_j /c_j}\) holds for any \({1 \leq j \leq n,\ j \neq i}\), the functional equation has a nonconstant solution if and only if there are field automorphisms \({\phi_1, \ldots, \phi_k}\) of \({\mathbb{C}}\) such that \({\phi_1 \cdots \phi_k}\) is a solution of the equation.
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G. Kiss was supported by Hungarian Scientific Foundation grant no. 72655.
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Kiss, G., Varga, A. Existence of nontrivial solutions of linear functional equations. Aequat. Math. 88, 151–162 (2014). https://doi.org/10.1007/s00010-013-0212-z
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DOI: https://doi.org/10.1007/s00010-013-0212-z