Self-organized regime switching in null-recurrent dynamics
零常返动态中的自组织状态切换
Based on discrete observations $X_0,X_Δ,\dots, X_{nΔ}$ for $Δ=n^{-γ}$ with $γ\in [0,1)$ of the null-recurrent dynamic $dX_t = σ(X_t)dW_t$ with a Brownian motion $W$ and $σ(x)=α\mathbb{1}\{x<ρ\} + β\mathbb{1}\{x\geq ρ\}$, we derive rate of convergence and limiting distribution of the profile MLE for $ρ$. This includes low-frequency asymptotics ($γ=0$) for which the observations form a null-recurrent Markov chain. The derived non-standard limit is the argsup over a doubly…