Sequential unanimity voting rules for binary social choice - Stergios Athanasoglou (Università di Milano - Bicocca)

Consider a group of voters that needs to decide between two candidates. In this setting, we propose a novel family of neutral and strategy-proof rules, which we call sequential unanimity rules. By demonstrating its formal equivalence to the M-winning coalition rules of Moulin (1983), we show that a subfamily of sequential unanimity rules, which we refer to as ``essential", is characterized by neutrality and strategy-proofness. We establish our results by developing algorithms that transform a given M-winning coalition rule into an equivalent sequential unanimity rule and vice versa. Since M-winning coalition rules are identical to strong simple games, the analysis is relevant to this strand of the game-theoretic literature as well. Finally, our approach can be extended to accommodate the full preference domain in which voters may be indifferent between candidates.