The Ergodic Linear-Quadratic Optimal Control Problems for Stochastic Mean-Field Systems with Periodic Coefficients
Jiacheng Wu, Qi Zhang
TL;DR
The paper tackles ergodic linear-quadratic control for stochastic mean-field systems with $\tau$-periodic coefficients. It develops a periodic-measure framework and periodic Riccati equations to convert the infinite-horizon ergodic cost into a finite-horizon problem on one period, enabling explicit closed-loop controls. The main contributions are the existence and characterization of periodic measures, the derivation of periodic Riccati equations and a linear ODE that yield a closed-form optimal control, and an illustrative 2D example confirming the theory. This provides a rigorous, practically applicable method for long-run optimization in large-scale systems subject to periodic environments.
Abstract
In this paper, we concern with the ergodic linear-quadratic closed-loop optimal control problems, in which the state equation is the mean-field stochastic differential equation with periodic coefficients. We first study the asymptotic behavior of the solution to the state equation and get a family of periodic measures depending on time variables within a period from the convergence of transition probabilities. Then, with the help of periodic measures and periodic Riccati equations, we transform the ergodic cost functional on infinite horizon into an equivalent cost functional on a single periodic interval without limit, and present the closed-loop optimal controls for our concerned control system. Finally, an example is given to demonstrate the applications of our theoretical results.
