VJE Seminar: Robert A. Becker (Indiana U, Bloomington)
Recursive Utility and Thompson Aggregators: The Recovery Theorem
Abstract: We reconsider the theory of Thompson aggregators proposed by Marinacci and Montrucchio. First, we prove a variant of their Recovery Theorem estabilishing the existence of extremal solutions to the Koopmans equation. Our approach applies the constructive Tarski-Kantorovich Fixed Point Theorem rather than the nonconstructive Tarski Theorem employed in their paper. We verify the Koopmans operator has the order continuity property that underlies invoking Tarski-Kantorovich. Then, undermore restrictive conditions, we demonstrate there is a unique solution to the Koopmans equation. Our proof is based on concave operator techniques as first developed by Kransosels'kii. This differs from Marinacci and Montrucchio's proof as well as proofs given by Martins-da-Rocha and Vailakis.