Approximate EFX and Exact tEFX Allocations for Indivisible Chores: Improved Algorithms

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Main Authors: Afshinmehr, Mahyar, Ansaripour, Matin, Danaei, Alireza, Mehlhorn, Kurt
Format: Preprint
Published: 2024
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author Afshinmehr, Mahyar
Ansaripour, Matin
Danaei, Alireza
Mehlhorn, Kurt
author_facet Afshinmehr, Mahyar
Ansaripour, Matin
Danaei, Alireza
Mehlhorn, Kurt
contents We explore the fair distribution of a set of $m$ indivisible chores among $n$ agents, where each agent's costs are evaluated using a monotone cost function. Our focus lies on two fairness criteria: envy-freeness up to any item (EFX) and a relaxed notion, namely envy-freeness up to the transfer of any item (tEFX). We demonstrate that a 2-approximate EFX allocation exists and is computable in polynomial time for three agents with subadditive cost functions, improving upon the previous $(2 + \sqrt{6})$ approximation for additive cost functions. This result requires extensive case analysis. Christoforidis et al. (IJCAI'24) independently claim the same approximation for additive cost functions; however, we provide a counter-example to their algorithm. We expand the number of agents to any number to get the same approximation guarantee with the assumption of partially identical ordering (IDO) for the cost functions. Additionally, we establish that a tEFX allocation is achievable for three agents if one has an additive 2-ratio bounded cost function, while the others may have general monotone cost functions. This is an improvement from the prior requirement of two agents with additive 2-ratio bounded cost functions. This allocation can also be extended to agent groups with identical valuations. Further, we show various analyses of EFX allocations for chores, such as the relaxations for additive $α$-ratio-bounded cost functions.
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id arxiv_https___arxiv_org_abs_2410_18655
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Approximate EFX and Exact tEFX Allocations for Indivisible Chores: Improved Algorithms
Afshinmehr, Mahyar
Ansaripour, Matin
Danaei, Alireza
Mehlhorn, Kurt
Computer Science and Game Theory
We explore the fair distribution of a set of $m$ indivisible chores among $n$ agents, where each agent's costs are evaluated using a monotone cost function. Our focus lies on two fairness criteria: envy-freeness up to any item (EFX) and a relaxed notion, namely envy-freeness up to the transfer of any item (tEFX). We demonstrate that a 2-approximate EFX allocation exists and is computable in polynomial time for three agents with subadditive cost functions, improving upon the previous $(2 + \sqrt{6})$ approximation for additive cost functions. This result requires extensive case analysis. Christoforidis et al. (IJCAI'24) independently claim the same approximation for additive cost functions; however, we provide a counter-example to their algorithm. We expand the number of agents to any number to get the same approximation guarantee with the assumption of partially identical ordering (IDO) for the cost functions. Additionally, we establish that a tEFX allocation is achievable for three agents if one has an additive 2-ratio bounded cost function, while the others may have general monotone cost functions. This is an improvement from the prior requirement of two agents with additive 2-ratio bounded cost functions. This allocation can also be extended to agent groups with identical valuations. Further, we show various analyses of EFX allocations for chores, such as the relaxations for additive $α$-ratio-bounded cost functions.
title Approximate EFX and Exact tEFX Allocations for Indivisible Chores: Improved Algorithms
topic Computer Science and Game Theory
url https://arxiv.org/abs/2410.18655