,
Ayumi Igarashi
,
Naoyuki Kamiyama
,
Warut Suksompong
Creative Commons Attribution 4.0 International license
Fairly allocating indivisible goods is a frequently occurring task in everyday life. Given an initial allocation of the goods, we consider the problem of reforming it via a sequence of exchanges to attain fairness in the form of envy-freeness up to one good (EF1). We present a vast array of results on the complexity of determining whether it is possible to reach an EF1 allocation from the initial allocation and, if so, the minimum number of exchanges required. In particular, we uncover several distinctions based on the number of agents involved and their utility functions. Furthermore, we derive essentially tight bounds on the worst-case number of exchanges needed to achieve EF1.
@InProceedings{yuen_et_al:LIPIcs.ISAAC.2025.54,
author = {Yuen, Sheung Man and Igarashi, Ayumi and Kamiyama, Naoyuki and Suksompong, Warut},
title = {{Reforming an Unfair Allocation by Exchanging Goods}},
booktitle = {36th International Symposium on Algorithms and Computation (ISAAC 2025)},
pages = {54:1--54:21},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-408-6},
ISSN = {1868-8969},
year = {2025},
volume = {359},
editor = {Chen, Ho-Lin and Hon, Wing-Kai and Tsai, Meng-Tsung},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2025.54},
URN = {urn:nbn:de:0030-drops-249626},
doi = {10.4230/LIPIcs.ISAAC.2025.54},
annote = {Keywords: fair division, indivisible goods, envy-freeness, exchanges}
}