Stability Under Valuation Updates in Coalition Formation

Fuente: arXiv
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Autores principales: Frank, Fabian, Novaković, Matija, Romen, René
Formato: Preprint
Publicado: 2026
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author Frank, Fabian
Novaković, Matija
Romen, René
author_facet Frank, Fabian
Novaković, Matija
Romen, René
contents Coalition formation studies how to partition a set of agents into disjoint coalitions under consideration of their preferences. We study the classical objective of stability in a variant of additively separable hedonic games where agents can change their valuations. Our objective is to find a stable partition after each change. To minimize the reconfiguration cost, we search for nearby stable coalition structures. Our focus is on stability concepts based on single-agent deviations. We present a detailed picture of the complexity of finding nearby stable coalition structures in additively separable hedonic games, for both symmetric and non-symmetric valuations. Our results show that the problem is NP-complete for Nash stability, individual stability, contractual Nash stability, and contractual individual stability. We complement these results by presenting polynomial-time algorithms for contractual Nash stability and contractual individual stability under restricted symmetric valuations. Finally, we show that these algorithms guarantee a bounded average distance over long sequences of updates.
format Preprint
id arxiv_https___arxiv_org_abs_2602_21041
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Stability Under Valuation Updates in Coalition Formation
Frank, Fabian
Novaković, Matija
Romen, René
Computer Science and Game Theory
Multiagent Systems
Coalition formation studies how to partition a set of agents into disjoint coalitions under consideration of their preferences. We study the classical objective of stability in a variant of additively separable hedonic games where agents can change their valuations. Our objective is to find a stable partition after each change. To minimize the reconfiguration cost, we search for nearby stable coalition structures. Our focus is on stability concepts based on single-agent deviations. We present a detailed picture of the complexity of finding nearby stable coalition structures in additively separable hedonic games, for both symmetric and non-symmetric valuations. Our results show that the problem is NP-complete for Nash stability, individual stability, contractual Nash stability, and contractual individual stability. We complement these results by presenting polynomial-time algorithms for contractual Nash stability and contractual individual stability under restricted symmetric valuations. Finally, we show that these algorithms guarantee a bounded average distance over long sequences of updates.
title Stability Under Valuation Updates in Coalition Formation
topic Computer Science and Game Theory
Multiagent Systems
url https://arxiv.org/abs/2602.21041