Rank Maximal Equal Contribution: A Probabilistic Social Choice Function

H. Aziz, P. Luo, C. Rizkallah
AAAI 2018
Abstract
When aggregating preferences of agents via voting, two desirable goals are to incentivize agents to participate in the voting process and then identify outcomes that are Pareto efficient. We consider participation as formalized by Brandl, Brandt, and Hofbauer (2015) based on the stochastic dominance (SD) relation. We formulate a new rule called RMEC (Rank Maximal Equal Contribution) that is polynomial-time computable, ex post efficient and satisfies the strongest notion of participation. It also satisfies many other desirable fairness properties. The rule suggests a general approach to achieving very strong participation, ex post efficiency and fairness.

Experiments:

Election type Culture Candidates Voters Instances Parameters
Ordinal exhaustive {4} {4} None None
Ordinal Impartial Culture [4-8] [4-8] 1000 None
Ordinal Impartial Culture [4-8] [4-8] 10000 None