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arXiv 1010.3604math.PRmath.STstat.TH
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多维扩散方程的一致中心极限定理

Uniform Central Limit Theorems for Multidimensional Diffusions

Angelika Rohde, Claudia Strauch

摘要:

最近研究表明,由于扩散局部时间的存在,基于标量扩散的经验过程的规则性行为与经典经验过程相比存在显着差异。除了建立强大的平行经典理论,如Ossiander的括号CLT和一般的Giné-Zinn CLT的一致有界的家庭的功能,我们发现增加的规律性也为多元遍历扩散,假设不变的措施是有限的勒贝格密度$π$。这种影响随着维度的增加而减小,但始终存在。利用连续Markov过程的鞅和加性泛函的指数不等式以及高斯过程的样本路径行为的一般链界的特征,给出了与经典iid设置的细微差别。为了揭示这一现象,我们研究了经验扩散过程的平滑版本。证明了在充要条件下,当$d=2$维数的带宽为指数级时,当参数$β> d/2$的带宽为强欠光滑时,在$d\geq 3$情形下,当漂移和扩散系数的坐标属于某个参数为$β$的Hölder球时,光滑经验扩散过程的一致弱收敛也能发生.

英文摘要:

It has recently been shown that there are substantial differences in the regularity behavior of the empirical process based on scalar diffusions as compared to the classical empirical process, due to the existence of diffusion local time. Besides establishing strong parallels to classical theory such as Ossiander's bracketing CLT and the general Giné-Zinn CLT for uniformly bounded families of functions, we find increased regularity also for multivariate ergodic diffusions, assuming that the invariant measure is finite with Lebesgue density $π$. The effect is diminishing for growing dimension but always present. The fine differences to the classical iid setting are worked out using exponential inequalities for martingales and additive functionals of continuous Markov processes as well as the characterization of the sample path behavior of Gaussian processes by means of the generic chaining bound. To uncover the phenomenon, we study a smoothed version of the empirical diffusion process. It turns out that uniform weak convergence of the smoothed empirical diffusion process under necessary and sufficient conditions can take place with even exponentially small bandwidth in dimension $d=2$, and with strongly undersmoothing bandwidth choice for parameters $β> d/2$ in case $d\geq 3$, assuming that the coordinates of drift and diffusion coefficient belong to some Hölder ball with parameter $β$.

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