Rank Aggregation by Dissatisfaction Minimisation in the Unavailable Candidate Model.

In this paper, we extend the unavailable candidate model (Tyler Lu and Craig Boutilier, The Unavailable Candidate Model : a Decision-Theoretic View of Social Choice, 2010) and present two new voting rules based on a finer notion of disagreement, called dissatisfaction, which depends on the ranks of the candidates, considered among all the candidates ( ante dissatisfaction rule) or only among the available candidates ( post dissatisfaction rule). We provide algorithmic results for the two rules and show that apparently very different voting rules such as scoring rules or Kemeny rule can be unified under the same aggregation concept: expectation of dissatisfaction under the availability distribution.