Avoiding Social Disappointment in Elections.

Mechanism design is concerned with settings where a policy maker (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 real-world situations, under special circumstances, the result of the election does not respect the purpose of those who execute it and the election leads to the dissatisfaction of a large number of people and in some cases causes polarization in societies. To analyze these situations, we introduce notions called social frustration and social disappointment and show which voting rules can prevent them in elections. In addition, we propose new protocols 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 empirically compared our protocols with seven well-known voting protocols and we observed that our protocols are capable of preventing social disappointment and are more robust against manipulations.