On the exact distributional asymptotics for the supremum of a random walk with increments in a class of light-tailed distributions

Abstract

We study the distribution of the maximum $M$ of a random walk whose increments have a distribution with negative mean and belonging, for some ${\hat{I}}^3>0$, to a subclass of the class ${\mathcal{S}}_{\hat{I}}^3$--see, for example, Chover, Ney, and Wainger (1973). For this subclass we give a probabilistic derivation of the asymptotic tail distribution of $M$, and show that extreme values of $M$ are in general attained through some single large increment in the random walk near the beginning of its trajectory. We also give some results concerning the ``spatially local'' asymptotics of the distribution of $M$, the maximum of the stopped random walk for various stopping times, and various bounds.

10 pages, minor revision of discussion, correction of typos, and additional references