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arXiv 1808.07033math.PR
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一般状态空间上马尔可夫链的定量收缩率

Quantitative contraction rates for Markov chains on general state spaces

Andreas Eberle, Mateusz B. Majka

摘要:

我们研究了量化Kantorovich($L^1$ Wasserstein)距离中Markov转移核的收缩系数的问题。对于扩散过程,收缩率的相对精确的定量界限最近已通过结合适当的耦合精心设计的康托洛维奇距离。在本文中,我们部分地将这种方法从扩散到马尔可夫链。我们推导出一般状态空间上的马尔可夫链的收缩率的定量下界,如果动力学是由小的局部移动主导的,则该下界是强大的。对于具有各向同性转移核的$\mathbb{R^d}$上的马尔可夫链,可以有效地使用一般边界以及结合最大耦合和反射耦合的耦合。结果被应用到欧拉离散的随机微分方程的非全局压缩漂移,和大都会调整Langevin算法的抽样从一类概率测度的高维状态空间,不是全球性的日志凹。

英文摘要:

We investigate the problem of quantifying contraction coefficients of Markov transition kernels in Kantorovich ($L^1$ Wasserstein) distances. For diffusion processes, relatively precise quantitative bounds on contraction rates have recently been derived by combining appropriate couplings with carefully designed Kantorovich distances. In this paper, we partially carry over this approach from diffusions to Markov chains. We derive quantitative lower bounds on contraction rates for Markov chains on general state spaces that are powerful if the dynamics is dominated by small local moves. For Markov chains on $\mathbb{R^d}$ with isotropic transition kernels, the general bounds can be used efficiently together with a coupling that combines maximal and reflection coupling. The results are applied to Euler discretizations of stochastic differential equations with non-globally contractive drifts, and to the Metropolis adjusted Langevin algorithm for sampling from a class of probability measures on high dimensional state spaces that are not globally log-concave.

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