Exit-and-Join Dynamics and Equilibrium in Continuum Cooperative Games
- URL: http://arxiv.org/abs/2606.28824v1
- Date: Sat, 27 Jun 2026 09:17:07 GMT
- Title: Exit-and-Join Dynamics and Equilibrium in Continuum Cooperative Games
- Abstract summary: We develop a continuum theory of exit-and-join coalition dynamics in nonatomic cooperative games.<n>We derive mean-field dynamics from decentralized switching rules and show that payoff-difference switching recovers replicator dynamics.<n>The proposed theory unifies cooperative value allocation, noncooperative coalition mobility, mean-field dynamics, evolutionary game theory, and population games.
- Score: 20.036142577511455
- License: http://creativecommons.org/licenses/by-nc-sa/4.0/
- Abstract: This paper develops a continuum theory of exit-and-join coalition dynamics in nonatomic cooperative games. We extend the Aumann-Shapley value and the Aumann-Drèze value to coalition structures in which each coalition is treated as a restricted nonatomic game, yielding a marginal-contribution-based payoff density that governs incentives for agents to remain in, exit, or join coalitions. We derive deterministic mean-field dynamics from decentralized switching rules and show that payoff-difference switching recovers replicator dynamics as a special case. We characterize exit-and-join equilibrium by the absence of profitable positive-mass deviations and prove its equivalence with stationarity of the induced mass dynamics under incentive-compatible and strictly payoff-responsive switching rates. For mass-based cooperative games, we construct a Lyapunov function and establish global convergence under strict concavity. We further show that the equilibrium is equivalent to a Wardrop equilibrium of an induced nonatomic population game and admits a variational inequality formulation. The framework is extended to incorporate switching costs and endogenous coalition acceptance rules, leading to constrained equilibria characterized by quasi-variational inequalities. The proposed theory unifies cooperative value allocation, noncooperative coalition mobility, mean-field dynamics, evolutionary game theory, and population games within a common framework for analyzing coalition formation and adaptation in large-scale multi-agent systems.
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