Linear-Quadratic Mean Field Stackelberg Stochastic Differential Game with Partial Information and Common Noise
Yu Si, Jingtao Shi
TL;DR
The paper addresses a linear-quadratic mean-field Stackelberg stochastic differential game with partial information and common noise, involving a leader and a large follower population. It develops a limiting mean-field formulation as $N\to\infty$ with a frozen limit $z(t)$ and derives open-loop and state-feedback decentralized strategies for both followers and the leader using the stochastic maximum principle and optimal filtering, under partial information. Central to the approach are CMF-FBSDEs and Riccati equations that yield explicit follower and leader strategies, with a dimension-expansion technique delivering a feedback form for the leader. The main result proves that these decentralized strategies constitute an $\\varepsilon$-Stackelberg-Nash equilibrium for the original finite-population game, with rigorous error bounds showing mean-field convergence, and numerical experiments corroborating the theoretical findings.
Abstract
This paper is concerned with a linear-quadratic mean field Stackelberg stochastic differential game with partial information and common noise, which contains a leader and a large number of followers. To be specific, the followers face a large population Nash game after the leader first announces his strategy, while the leader will then optimize his own cost functional on consideration of the followers' reactions. The state equation of the leader and followers are both general stochastic differential equations, where the diffusion terms contain both the control and state variables. However, the followers' average state terms enter into the drift term of the leader's state equation, reflecting that the leader's state is influenced by the followers' states. By virtue of stochastic maximum principle with partial information and optimal filter technique, we deduce the open-loop adapted decentralized strategies and feedback decentralized strategies of this leader-followers system, and demonstrate that the decentralized strategies are the corresponding $\varepsilon$-Stackelberg-Nash equilibrium.
