A particle system approach towards the global well-posedness of master equations for potential mean field games of control
Huafu Liao, Chenchen Mou
TL;DR
This work addresses the global well-posedness of HJB/master equations for generalized mean field control and potential mean field games of control by combining a particle-system analysis with probabilistic mean-field techniques. The authors construct local-in-time solutions via a mean-field stochastic maximum principle, obtain uniform a priori estimates through displacement convexity, and bootstrap them to global well-posedness, including degenerate-noise limits. They establish propagation of chaos with explicit convergence rates, relate the particle-system decoupling field to the master-field, and derive Lipschitz approximations to optimal feedbacks along with a quantitatively justified approximate Nash equilibrium for finite N. The results provide a rigorous bridge between finite-particle control problems and their mean-field limits, with direct implications for numerical schemes and stability analyses in generalized MFC and MFGC settings.
Abstract
This paper studies the $N$-particle systems as well as the HJB/master equations for a class of generalized mean field control (MFC) problems and the corresponding potential mean field games of control (MFGC). A local in time classical solution for the HJB equation is generated via a probabilistic approach based on the mean field maximum principle. Given an extension of the so called displacement convexity condition, we obtain the uniform estimates on the HJB equation for the $N$-particle system. Such estimates imply the displacement convexity/semi-concavity and thus the prior estimates on the solution to the HJB equation for generalized MFC problems. The global well-posedness of HJB/master equation for generalized MFC/potential MFGC is then proved thanks to the local well-posedness and the prior estimates. In view of the nature of the displacement convexity condition, such well-posedness is also true for the degenerated case. Our analysis on the $N$-particle system also induces an Lipschitz approximator to the optimal feedback function in generalized MFC/potential MFGC where an algebraic convergence rate is obtained. Furthermore, an alternative approximate Nash equilibrium is proposed based on the $N$-particle system, where the approximation error is quantified thanks to the aforementioned uniform estimates.
