The Proportional Veto Principle for Approval Ballots

The proportional veto principle, which captures the idea that a candidate vetoed by a large group of voters should not be chosen, has been studied for ranked ballots in single-winner voting. We introduce a version of this principle for approval ballots, which we call flexible-voter representation (FVR). We show that while the approval voting rule and other natural scoring rules provide the optimal FVR guarantee only for some flexibility threshold, there exists a scoring rule that is FVR-optimal for all thresholds simultaneously. We also extend our results to multi-winner voting.

@article{halpern2025_2505.01395,
  title={ The Proportional Veto Principle for Approval Ballots },
  author={ Daniel Halpern and Ariel D. Procaccia and Warut Suksompong },
  journal={arXiv preprint arXiv:2505.01395},
  year={ 2025 }
}