The price of connectivity in fair division

We study the allocation of indivisible goods that form an undirected graph and quantify the loss of fairness when we impose a constraint that each agent must receive a connected subgraph. Our focus is on well-studied fairness notions including envy-freeness and maximin share fairness. We introduc...

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Main Authors: Bei, Xiaohui, Igarashi, Ayumi, Lu, Xinhang, Suksompong, Warut
Other Authors: School of Physical and Mathematical Sciences
Format: Journal Article
Language:English
Published: 2022
Subjects:
Online Access:https://hdl.handle.net/10356/161276
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author Bei, Xiaohui
Igarashi, Ayumi
Lu, Xinhang
Suksompong, Warut
author2 School of Physical and Mathematical Sciences
author_facet School of Physical and Mathematical Sciences
Bei, Xiaohui
Igarashi, Ayumi
Lu, Xinhang
Suksompong, Warut
author_sort Bei, Xiaohui
collection NTU
description We study the allocation of indivisible goods that form an undirected graph and quantify the loss of fairness when we impose a constraint that each agent must receive a connected subgraph. Our focus is on well-studied fairness notions including envy-freeness and maximin share fairness. We introduce the price of connectivity to capture the largest gap between the graph-specific and the unconstrained maximin share, and derive bounds on this quantity which are tight for large classes of graphs in the case of two agents and for paths and stars in the general case. For instance, with two agents we show that for biconnected graphs it is possible to obtain at least $3/4$ of the maximin share with connected allocations, while for the remaining graphs the guarantee is at most $1/2$. In addition, we determine the optimal relaxation of envy-freeness that can be obtained with each graph for two agents, and characterize the set of trees and complete bipartite graphs that always admit an allocation satisfying envy-freeness up to one good (EF1) for three agents. Our work demonstrates several applications of graph-theoretic tools and concepts to fair division problems.
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spelling ntu-10356/1612762023-02-28T20:11:30Z The price of connectivity in fair division Bei, Xiaohui Igarashi, Ayumi Lu, Xinhang Suksompong, Warut School of Physical and Mathematical Sciences Science::Mathematics Fair Division Envy-Freeness We study the allocation of indivisible goods that form an undirected graph and quantify the loss of fairness when we impose a constraint that each agent must receive a connected subgraph. Our focus is on well-studied fairness notions including envy-freeness and maximin share fairness. We introduce the price of connectivity to capture the largest gap between the graph-specific and the unconstrained maximin share, and derive bounds on this quantity which are tight for large classes of graphs in the case of two agents and for paths and stars in the general case. For instance, with two agents we show that for biconnected graphs it is possible to obtain at least $3/4$ of the maximin share with connected allocations, while for the remaining graphs the guarantee is at most $1/2$. In addition, we determine the optimal relaxation of envy-freeness that can be obtained with each graph for two agents, and characterize the set of trees and complete bipartite graphs that always admit an allocation satisfying envy-freeness up to one good (EF1) for three agents. Our work demonstrates several applications of graph-theoretic tools and concepts to fair division problems. Ministry of Education (MOE) Published version This work was partially supported by the Ministry of Education, Singapore, under its Academic Research Fund Tier 1 (RG23/20), by the KAKENHI Grant-in-Aid for JSPS Fellows(18J00997), by the European Research Council (ERC) under grant 639945 (ACCORD), by an NUS Start-Up Grant, and by JST, ACT-X. 2022-08-23T06:51:37Z 2022-08-23T06:51:37Z 2022 Journal Article Bei, X., Igarashi, A., Lu, X. & Suksompong, W. (2022). The price of connectivity in fair division. SIAM Journal On Discrete Mathematics, 36(2), 1156-1186. https://dx.doi.org/10.1137/20M1388310 0895-4801 https://hdl.handle.net/10356/161276 10.1137/20M1388310 2-s2.0-85132235267 2 36 1156 1186 en RG23/20 SIAM Journal on Discrete Mathematics © 2022 SIAM. Published by SIAM under the terms of the Creative Commons 4.0 license. application/pdf
spellingShingle Science::Mathematics
Fair Division
Envy-Freeness
Bei, Xiaohui
Igarashi, Ayumi
Lu, Xinhang
Suksompong, Warut
The price of connectivity in fair division
title The price of connectivity in fair division
title_full The price of connectivity in fair division
title_fullStr The price of connectivity in fair division
title_full_unstemmed The price of connectivity in fair division
title_short The price of connectivity in fair division
title_sort price of connectivity in fair division
topic Science::Mathematics
Fair Division
Envy-Freeness
url https://hdl.handle.net/10356/161276
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