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arXiv 1607.03545math.PR
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以大指数时间位置为条件的马尔可夫过程

Markov processes conditioned on their location at large exponential times

Steven N. Evans, Alexandru Hening

摘要:

设$(X_t)_{t \ge 0}$是一个负漂移的一维布朗运动$-μ$ .在独立的指数随机时间,条件化这个过程处于状态$0$是有意义的,如果我们在指数时间杀死条件化的过程,那么得到的过程是马尔可夫的。如果我们让随机时间的速率参数变为$0$,那么被杀死的马尔可夫过程的极限就像$X$被限制为击中$0$,在这之后,它的行为就像$X$在最后一次$X$访问$0$时被杀死一样。等价地,极限过程具有被杀死的“bang-bang”布朗运动的动力学,当它为负时,它像具有正漂移$+μ$的布朗运动一样演化,当它为正时,它像具有负漂移$-μ$的布朗运动一样演化,并且根据在$0$上花费的局部时间被杀死。这一结果的一个扩展具有很大的普遍性Borel右过程的条件是在某种状态$a$在指数随机时间,在这个时候,他们被杀死。我们的证据涉及了解坎贝尔措施与当地时间,使用的游览理论,并发展一个合适的模拟的“砰-砰”建设一般马尔可夫过程。作为例子,我们考虑的特殊情况下,瞬态Borel右过程是一个一维扩散。通过其无穷小生成器的限制条件和杀死的过程的特点导致调查的$h$ -变换的瞬态一维扩散过程,超越了已知的,是独立的兴趣。

英文摘要:

Suppose that $(X_t)_{t \ge 0}$ is a one-dimensional Brownian motion with negative drift $-μ$. It is possible to make sense of conditioning this process to be in the state $0$ at an independent exponential random time and if we kill the conditioned process at the exponential time the resulting process is Markov. If we let the rate parameter of the random time go to $0$, then the limit of the killed Markov process evolves like $X$ conditioned to hit $0$, after which time it behaves as $X$ killed at the last time $X$ visits $0$. Equivalently, the limit process has the dynamics of the killed "bang--bang" Brownian motion that evolves like Brownian motion with positive drift $+μ$ when it is negative, like Brownian motion with negative drift $-μ$ when it is positive, and is killed according to the local time spent at $0$. An extension of this result holds in great generality for Borel right processes conditioned to be in some state $a$ at an exponential random time, at which time they are killed. Our proofs involve understanding the Campbell measures associated with local times, the use of excursion theory, and the development of a suitable analogue of the "bang--bang" construction for general Markov processes. As examples, we consider the special case when the transient Borel right process is a one-dimensional diffusion. Characterizing the limiting conditioned and killed process via its infinitesimal generator leads to an investigation of the $h$-transforms of transient one-dimensional diffusion processes that goes beyond what is known and is of independent interest.

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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