7 października 2025 11:00
[Seminarium ZOK] Krzysztof Sornat: "Robust Committee Voting, or The Other Side of Representation"
We study approval-based committee voting from a novel perspective.
While extant work largely centers around proportional representation
of the voters, we shift our focus to the candidates while preserving
proportionality. Intuitively, candidates supported by similar voter
groups should receive comparable representation. Since deterministic
voting rules cannot achieve this ideal, we develop randomized voting
rules that satisfy ex-ante neutrality, monotonicity, and continuity,
while maintaining strong ex-post proportionality guarantees.
Continuity of the candidate selection probabilities proves to be the
most demanding of our ex-ante desiderata. We provide it via voting
rules that are algorithmically stable, a stronger notion of robustness
which captures the continuity of the committee distribution under
small changes.
Joint work with Gregory Kehne and Ulrike Schmidt-Kraepelin.
Full version: https://arxiv.org/abs/2506.18643
EC-25 version: https://dl.acm.org/doi/10.1145/3736252.3742676