Analysis of Equilibria in Iterative Voting Schemes

Following recent analyses of iterative voting and its effects on plurality vote outcomes, we provide a general characterisation of the set of equilibria attainable by iterative plurality voting. We show that deciding whether a given profile is an iteratively reachable equilibrium is NP-complete; however, if truth bias is added, we show that it is possible to determine all equilibria in polynomial time. Furthermore, we fully characterise the set of iterative truth-biased equilibria. We then examine the model of lazy voters, in which a voter may choose to abstain from the election, showing that the iterative voting process in this case converges to a stable state. As in the case with truth bias, we show that it takes at most polynomial time to find stable states that are Nash equilibria.

• Type: Journal
• Year: 2015
• Where: AAAI
• Authors: Zinovi Rabinovich, Svetlana Obraztsova, Omer Lev, Evangelos Markakis, Jeffrey S. Rosenschein
• Keywords: AAAI 2015, Intelligent Agents