Héctor Hermida-Rivera (University of East Anglia) will present his job market paper “Stable Voting Rules“ on March 20th at 10 AM, room QA 406. One-to-one meetings with the speaker can be arranged; please contact the seminar organizers, Dr. Noémie Cabau (email@example.com) and Dr. Arseniy Samsonov (firstname.lastname@example.org).
This paper introduces a flexible notion of stability for voting rules that can be used with any equilibrium concept. Theorem 1 shows that if players’ utility function satisfies four natural axioms, a voting rule is stable in Nash equilibria if and only if it has a unique minimal winning coalition. Theorem 2 shows that under the same four axioms, the set of stable voting rules in undominated Nash equilibria contains the set of voting rules with a unique minimal winning coalition and is contained in the set of voting rules with non-empty intersection of minimal winning coalitions. Finally, Theorems 3 to 6 rely on these results to partially characterise the set of self-stable constitutions, where a constitution is a pair of voting rules: an ordinary one for routine issues, and an extraordinary one for amendments.