Stackelberg Voting Games: Computational Aspects and Paradoxes

We consider settings in which voters vote in sequence, each voter knows the votes of the earlier voters and the preferences of the later voters, and voters are strategic. This can be modeled as an extensive-form game of perfect information, which we call a Stackelberg voting game. We first propose a dynamic-programming algorithm for finding the backward-induction outcome for any Stackelberg voting game when the rule is anonymous; this algorithm is efficient if the number of alternatives is no more than a constant. We show how to use compilation functions to further reduce the time and space requirements. Our main theoretical results are paradoxes for the backwardinduction outcomes of Stackelberg voting games. We show that for any n 5 and any voting rule that satisfies nonimposition and with a low domination index, there exists a profile consisting of n voters, such that the backwardinduction outcome is ranked somewhere in the bottom two positions in almost every voter's preferen...

• Type: Conference
• Year: 2010
• Where: AAAI
• Authors: Lirong Xia, Vincent Conitzer
• Keywords: AAAI 2010, Backward-induction Outcome, Intelligent Agents, Stackelberg Voting Game, Voting Rules