Voting Methods to Prevent Social Disappointment in Elections
摘要
Mechanism design is concerned with settings where a policymaker (or social planner) faces the problem of aggregating the announced preferences of multiple agents into a collective (or social) system-wide decision. One of the most important ways for aggregating preference that has been used in multiagent systems is election. In an election, the aim is to select the candidate who reflects the common will of society. Despite the importance of this subject, in some situations the result of the election does not respect the purpose of those who execute it, and the election leads to dissatisfaction of a large amount of people and in some cases causes polarization in societies. To analyze these situations, we introduce a new notion called social disappointment, and we show which voting rules can prevent it in elections. In addition, we propose a new protocol to prevent social disappointment in elections. A version of the impossibility theorem is proved regarding social disappointment in elections, showing that there is no voting rule for four or more candidates that simultaneously satisfies avoiding social disappointment and Condorcet winner criteria. We give conditions under which our new protocol always selects the Condorcet winner under the assumption of single-peakness. We empirically compare our protocol with eight well-known other voting protocols and observe that our protocol is capable of preventing social disappointment and is more robust against manipulations.