The Complexity of Fair Division of Indivisible Items with Externalities

Fuente: arXiv
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Main Authors: Deligkas, Argyrios, Eiben, Eduard, Korchemna, Viktoriia, Schierreich, Šimon
Format: Preprint
Published: 2023
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author Deligkas, Argyrios
Eiben, Eduard
Korchemna, Viktoriia
Schierreich, Šimon
author_facet Deligkas, Argyrios
Eiben, Eduard
Korchemna, Viktoriia
Schierreich, Šimon
contents We study the computational complexity of fairly allocating a set of indivisible items under externalities. In this recently-proposed setting, in addition to the utility the agent gets from their bundle, they also receive utility from items allocated to other agents. We focus on the extended definitions of envy-freeness up to one item (EF1) and of envy-freeness up to any item (EFX), and we provide the landscape of their complexity for several different scenarios. We prove that it is NP-complete to decide whether there exists an EFX allocation, even when there are only three agents, or even when there are only six different values for the items. We complement these negative results by showing that when both the number of agents and the number of different values for items are bounded by a parameter the problem becomes fixed-parameter tractable. Furthermore, we prove that two-valued and binary-valued instances are equivalent and that EFX and EF1 allocations coincide for this class of instances. Finally, motivated from real-life scenarios, we focus on a class of structured valuation functions, which we term agent/item-correlated. We prove their equivalence to the ``standard'' setting without externalities. Therefore, all previous results for EF1 and EFX apply immediately for these valuations.
format Preprint
id arxiv_https___arxiv_org_abs_2308_08869
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The Complexity of Fair Division of Indivisible Items with Externalities
Deligkas, Argyrios
Eiben, Eduard
Korchemna, Viktoriia
Schierreich, Šimon
Computer Science and Game Theory
We study the computational complexity of fairly allocating a set of indivisible items under externalities. In this recently-proposed setting, in addition to the utility the agent gets from their bundle, they also receive utility from items allocated to other agents. We focus on the extended definitions of envy-freeness up to one item (EF1) and of envy-freeness up to any item (EFX), and we provide the landscape of their complexity for several different scenarios. We prove that it is NP-complete to decide whether there exists an EFX allocation, even when there are only three agents, or even when there are only six different values for the items. We complement these negative results by showing that when both the number of agents and the number of different values for items are bounded by a parameter the problem becomes fixed-parameter tractable. Furthermore, we prove that two-valued and binary-valued instances are equivalent and that EFX and EF1 allocations coincide for this class of instances. Finally, motivated from real-life scenarios, we focus on a class of structured valuation functions, which we term agent/item-correlated. We prove their equivalence to the ``standard'' setting without externalities. Therefore, all previous results for EF1 and EFX apply immediately for these valuations.
title The Complexity of Fair Division of Indivisible Items with Externalities
topic Computer Science and Game Theory
url https://arxiv.org/abs/2308.08869