Multiwinner Temporal Voting with Aversion to Change
Abstract
We study two-stage committee elections where voters have dynamic preferences over candidates; at each stage, a committee is chosen under a given voting rule. We are interested in identifying a winning committee for the second stage that overlaps as much as possible with the first-stage committee. We show a full complexity dichotomy for the class of Thiele rules: this problem is tractable for Approval Voting (AV) and hard for all other Thiele rules (including, in particular, Proportional Approval Voting and the Chamberlin-Courant rule). We extend this dichotomy to the greedy variants of Thiele rules. We also explore this problem from a parameterized complexity perspective for several natural parameters. We complement the theory with experimental analysis: e.g., we investigate the average number of changes in the committee as a function of changes in voters' preferences and the role of ties.
Keywords
Cite
@article{arxiv.2408.11017,
title = {Multiwinner Temporal Voting with Aversion to Change},
author = {Valentin Zech and Niclas Boehmer and Edith Elkind and Nicholas Teh},
journal= {arXiv preprint arXiv:2408.11017},
year = {2024}
}
Comments
Appears in the 27th European Conference on Artificial Intelligence (ECAI), 2024