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arXiv 1306.5446math.PR
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具有时间尺度分离的耦合扩散方程的大偏差

On large deviations of coupled diffusions with time scale separation

Anatolii A. Puhalskii

摘要:

我们考虑两个伊藤方程,演变在不同的时间尺度。方程是完全耦合的,在这个意义上,所有的系数可以取决于“慢”和“快”的过程和扩散项可以相关。“慢”过程中的扩散项很小。对于慢过程和快过程的经验测度的联合分布,得到了一个大偏差原理。通过对慢变量和快变量的投影,我们分别得到了关于平均框架中的大偏差和关于遍历扩散的经验测度的大偏差的新结果。主要结果的证明依赖于指数紧性蕴涵大偏差相对紧性的性质。通过分析指数鞅的大偏差极限,实现了大偏差率函数的识别。

英文摘要:

We consider two Ito equations that evolve on different time scales. The equations are fully coupled in the sense that all coefficients may depend on both the "slow" and the "fast" processes and the diffusion terms may be correlated. The diffusion term in the "slow" process is small. A large deviation principle is obtained for the joint distribution of the slow process and of the empirical measure of the fast process. By projecting on the slow and fast variables, we arrive at new results on large deviations in the averaging framework and on large deviations of the empirical measures of ergodic diffusions, respectively. The proof of the main result relies on the property that exponential tightness implies large deviation relative compactness. The identification of the large deviation rate function is accomplished by analysing the large deviation limit of an exponential martingale.

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