On hitting times and fastest strong stationary times for skip-free chains
On hitting times and fastest strong stationary times for skip-free chains
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关于无跳链的击球时间和最快强静止时间
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发表时间:
2007
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通讯作者:
J. A. Fill
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作者:
J. A. Fill
An (upward) skip-free Markov chain with the set of nonnegative integers as state space is a chain for which upward jumps may be only of unit size; there is no restriction on downward jumps. In a 1987 paper, Brown and Shao determined, for an irreducible continuous-time skip-free chain and any d, the passage time distribution from state 0 to state d. When the nonzero eigenvalues νj of the generator are all real, their result states that the passage time is distributed as the sum of d independent exponential random variables with rates νj. We give another proof of their theorem. In the case of birth-and-death chains, our proof leads to an explicit representation of the passage time as a sum of independent exponential random variables. Diaconis and Miclo recently obtained the first such representation, but our construction is much simpler. We obtain similar (and new) results for a fastest strong stationary time T of an ergodic continuous-time skip-free chain with stochastically monotone time-reversal started in state 0, and we also obtain discrete-time analogs of all our results. AMS 2000 subject classifications. Primary 60J25; secondary 60J35, 60J10, 60G40.