Pessimal Elections for Approximately Dominating Sets

Abstract

Condorcet's paradox is a foundational result in social choice theory, showing that no matter which candidate wins an election, a majority of voters may prefer some losing candidate. Worse still, even if the election can choose a committee of $k$ winners, some loser may beat every winner in a majority vote. Recent work showed that this obstruction can be sidestepped by relaxing the majority threshold. For all $\epsilon >0$, any election can select a committee of $O(1/{\epsilon }^2)$ winners such that no loser is preferred to every winner by $\frac{1}{2}+\epsilon$ fraction of voters. We present a simple construction, found by GPT-5.6 Sol Ultra, which proves that this result is tight up to a constant factor.