Single-Winner Voting on Matchings

Fuente: arXiv
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Hauptverfasser: Boehmer, Niclas, Dierking, Jessica
Format: Preprint
Veröffentlicht: 2026
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author Boehmer, Niclas
Dierking, Jessica
author_facet Boehmer, Niclas
Dierking, Jessica
contents We introduce a single-winner perspective on voting on matchings, in which voters have preferences over possible matchings in a graph, and the goal is to select a single collectively desirable matching. Unlike in classical matching problems, voters in our model are not part of the graph; instead, they have preferences over the entire matching. In the resulting election, the candidate space consists of all feasible matchings, whose exponential size renders standard algorithms for identifying socially desirable outcomes computationally infeasible. We study whether the computational tractability of finding such outcomes can be regained by exploiting the matching structure of the candidate space. Specifically, we provide a complete complexity landscape for questions concerning the maximization of social welfare, the construction and verification of Pareto optimal outcomes, and the existence and verification of Condorcet winners under one affine and two approval-based utility models. Our results consist of a mix of algorithmic and intractability results, revealing sharp boundaries between tractable and intractable cases, with complexity jumps arising from subtle changes in the utility model or solution concept.
format Preprint
id arxiv_https___arxiv_org_abs_2601_19653
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Single-Winner Voting on Matchings
Boehmer, Niclas
Dierking, Jessica
Computer Science and Game Theory
We introduce a single-winner perspective on voting on matchings, in which voters have preferences over possible matchings in a graph, and the goal is to select a single collectively desirable matching. Unlike in classical matching problems, voters in our model are not part of the graph; instead, they have preferences over the entire matching. In the resulting election, the candidate space consists of all feasible matchings, whose exponential size renders standard algorithms for identifying socially desirable outcomes computationally infeasible. We study whether the computational tractability of finding such outcomes can be regained by exploiting the matching structure of the candidate space. Specifically, we provide a complete complexity landscape for questions concerning the maximization of social welfare, the construction and verification of Pareto optimal outcomes, and the existence and verification of Condorcet winners under one affine and two approval-based utility models. Our results consist of a mix of algorithmic and intractability results, revealing sharp boundaries between tractable and intractable cases, with complexity jumps arising from subtle changes in the utility model or solution concept.
title Single-Winner Voting on Matchings
topic Computer Science and Game Theory
url https://arxiv.org/abs/2601.19653