On Coalitions and Stable Winners in Plurality

We consider elections under the Plurality rule, where all voters are assumed to act strategically. As there are typically many Nash equilibria for every preference profile, and strong equilibria do not always exist, we analyze the most stable outcomes according to their stability scores (the number of coalitions with an interest to deviate). We show a tight connection between the Maximin score of a candidate and the highest stability score of the outcomes where this candidate wins, and show that under mild conditions the Maximin winner will also be the winner in the most stable outcome under Plurality.

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