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arXiv 1806.07166math.PR
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具有重尾增量和渐近零漂移的马尔可夫链

Markov chains with heavy-tailed increments and asymptotically zero drift

Nicholas Georgiou, Mikhail V. Menshikov, Dimitri Petritis, Andrew R. Wade

摘要:

本文研究了$\mathbb{R}_+$,$\mathbb{R}$和$\mathbb{R}^2$上的马尔可夫链的常返/瞬态相变,其中链的增量具有指数在$(1,2)$中的重尾和渐近零均值.这是经典Lamperti问题的无穷方差模拟。例如,在$\mathbb{R}_+$上,我们证明了如果正增量的尾部对于指数$α\in (1,2)$约为$c y^{-α}$,并且如果在$x$处的漂移约为$b x^{-γ}$,则临界状态具有$γ= α-1$,并且复发/瞬变由$b + cπ\textrm{cosec} (πα)$的符号确定。在$\mathbb{R}$上,我们对瞬时是定向的还是振荡的进行了分类,并将Rogozin \& Foss的一个例子推广到一类在$\pm \infty$之间振荡的瞬时鞅.除了我们的复发/瞬态结果,我们也给尖锐的结果存在/不存在的时刻的通过时间。

英文摘要:

We study the recurrence/transience phase transition for Markov chains on $\mathbb{R}_+$, $\mathbb{R}$, and $\mathbb{R}^2$ whose increments have heavy tails with exponent in $(1,2)$ and asymptotically zero mean. This is the infinite-variance analogue of the classical Lamperti problem. On $\mathbb{R}_+$, for example, we show that if the tail of the positive increments is about $c y^{-α}$ for an exponent $α\in (1,2)$ and if the drift at $x$ is about $b x^{-γ}$, then the critical regime has $γ= α-1$ and recurrence/transience is determined by the sign of $b + cπ\textrm{cosec} (πα)$. On $\mathbb{R}$ we classify whether transience is directional or oscillatory, and extend an example of Rogozin \& Foss to a class of transient martingales which oscillate between $\pm \infty$. In addition to our recurrence/transience results, we also give sharp results on the existence/non-existence of moments of passage times.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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