EF1 Allocations for Identical Trilean and Separable Single-Peaked Valuations

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Main Authors: Bhaskar, Umang, Kumar, Gunjan, Pandit, Yeshwant, Rakshitha
Format: Preprint
Published: 2024
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author Bhaskar, Umang
Kumar, Gunjan
Pandit, Yeshwant
Rakshitha
author_facet Bhaskar, Umang
Kumar, Gunjan
Pandit, Yeshwant
Rakshitha
contents In the fair division of items among interested agents, envy-freeness is possibly the most favoured and widely studied formalisation of fairness. For indivisible items, envy-free allocations may not exist in trivial cases, and hence research and practice focus on relaxations, particularly envy-freeness up to one item (EF1). A significant reason for the popularity of EF1 allocations is its simple fact of existence. It is known that EF1 allocations exist for two agents with arbitrary valuations; agents with doubly-monotone valuations; agents with Boolean valuations; and identical agents with negative Boolean valuations. We consider two new but natural classes of valuations, and partly extend results on the existence of EF1 allocations to these valuations. Firstly, we consider trilean valuations - an extension of Boolean valuations - when the value of any subset is 0, $a$, or $b$ for any integers $a$ and $b$. Secondly, we define separable single-peaked valuations, when the set of items is partitioned into types. For each type, an agent's value is a single-peaked function of the number of items of the type. The value for a set of items is the sum of values for the different types. We prove EF1 existence for identical trilean valuations for any number of agents, and for separable single-peaked valuations for three agents. For both classes of valuations, we also show that EFX allocations do not exist.
format Preprint
id arxiv_https___arxiv_org_abs_2411_19881
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle EF1 Allocations for Identical Trilean and Separable Single-Peaked Valuations
Bhaskar, Umang
Kumar, Gunjan
Pandit, Yeshwant
Rakshitha
Computer Science and Game Theory
91B32, 91A68
F.2.0
In the fair division of items among interested agents, envy-freeness is possibly the most favoured and widely studied formalisation of fairness. For indivisible items, envy-free allocations may not exist in trivial cases, and hence research and practice focus on relaxations, particularly envy-freeness up to one item (EF1). A significant reason for the popularity of EF1 allocations is its simple fact of existence. It is known that EF1 allocations exist for two agents with arbitrary valuations; agents with doubly-monotone valuations; agents with Boolean valuations; and identical agents with negative Boolean valuations. We consider two new but natural classes of valuations, and partly extend results on the existence of EF1 allocations to these valuations. Firstly, we consider trilean valuations - an extension of Boolean valuations - when the value of any subset is 0, $a$, or $b$ for any integers $a$ and $b$. Secondly, we define separable single-peaked valuations, when the set of items is partitioned into types. For each type, an agent's value is a single-peaked function of the number of items of the type. The value for a set of items is the sum of values for the different types. We prove EF1 existence for identical trilean valuations for any number of agents, and for separable single-peaked valuations for three agents. For both classes of valuations, we also show that EFX allocations do not exist.
title EF1 Allocations for Identical Trilean and Separable Single-Peaked Valuations
topic Computer Science and Game Theory
91B32, 91A68
F.2.0
url https://arxiv.org/abs/2411.19881