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Main Authors: Hsu, Kevin, King, Valerie
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2501.13481
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author Hsu, Kevin
King, Valerie
author_facet Hsu, Kevin
King, Valerie
contents This paper addresses the problem of finding fair orientations of graphs of chores, in which each vertex corresponds to an agent, each edge corresponds to a chore, and a chore has zero marginal utility to an agent if its corresponding edge is not incident to the vertex corresponding to the agent. Recently, Zhou et al. (IJCAI, 2024) analyzed the complexity of deciding whether graphs containing a mixture of goods and chores have EFX orientations, and conjectured that deciding whether graphs containing only chores have EFX orientations is NP-complete. We resolve this conjecture by giving polynomial-time algorithms that find EF1 and EFX orientations of graphs containing only chores if they exist, even if there are self-loops. Remarkably, our result demonstrates a surprising separation between the case of goods and the case of chores, because deciding whether graphs containing only goods have EFX orientations was shown to be NP-complete by Christodoulou et al. (EC, 2023). In addition, we show the EF1 and EFX orientation problems for multigraphs to be NP-complete.
format Preprint
id arxiv_https___arxiv_org_abs_2501_13481
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Polynomial-Time Algorithms for Fair Orientations of Chores
Hsu, Kevin
King, Valerie
Computer Science and Game Theory
Artificial Intelligence
Discrete Mathematics
This paper addresses the problem of finding fair orientations of graphs of chores, in which each vertex corresponds to an agent, each edge corresponds to a chore, and a chore has zero marginal utility to an agent if its corresponding edge is not incident to the vertex corresponding to the agent. Recently, Zhou et al. (IJCAI, 2024) analyzed the complexity of deciding whether graphs containing a mixture of goods and chores have EFX orientations, and conjectured that deciding whether graphs containing only chores have EFX orientations is NP-complete. We resolve this conjecture by giving polynomial-time algorithms that find EF1 and EFX orientations of graphs containing only chores if they exist, even if there are self-loops. Remarkably, our result demonstrates a surprising separation between the case of goods and the case of chores, because deciding whether graphs containing only goods have EFX orientations was shown to be NP-complete by Christodoulou et al. (EC, 2023). In addition, we show the EF1 and EFX orientation problems for multigraphs to be NP-complete.
title Polynomial-Time Algorithms for Fair Orientations of Chores
topic Computer Science and Game Theory
Artificial Intelligence
Discrete Mathematics
url https://arxiv.org/abs/2501.13481