On the Ergodicity of Nonlinear Fokker–Planck Flows in L1(ℝd)
摘要
We prove that a nonlinear semigroup S(t) in L1(ℝd), d ≥ 3, associated with the nonlinear Fokker–Planck equation ut−∆β(u)+div(Db(u)u) = 0, u(0) = u0, in (0,∞)× ℝd, with suitable conditions imposed on the coefficients β : ℝ → ℝ, −D : ℝd → ℝd, and b : ℝ → ℝ, is mean ergodic. In particular, this implies the mean ergodicity of the time marginal laws for the solutions to the corresponding McKean–Vlasov stochastic differential equation. This completes the results established in [V. Barbu and M. Röckner, “The invariance principle for nonlinear Fokker–Planck equations,” J. Different. Equat., 315, 200–221 (2022)] on the nature of the corresponding omega-set ω (u0) for S(t) in the case where the flow S(t) in L1(ℝd) does not have a fixed point and, hence, the corresponding stationary Fokker–Planck equation has no solutions.