On Conditioning a Random Walk to Stay Nonnegative
Bertoin, J. ; Doney, R. A.
Ann. Probab., Tome 22 (1994) no. 4, p. 2152-2167 / Harvested from Project Euclid
Let $S$ be a real-valued random walk that does not drift to $\infty$, so $P(S_k \geq 0$ for all $k) = 0$. We condition $S$ to exceed $n$ before hitting the negative half-line, respectively, to stay nonnegative up to time $n$. We study, under various hypotheses, the convergence of these conditional laws as $n \rightarrow \infty$. First, when $S$ oscillates, the two approximations converge to the same probability law. This feature may be lost when $S$ drifts to $-\infty$. Specifically, under suitable assumptions on the upper tail of the step distribution, the two approximations then converge to different probability laws.
Publié le : 1994-10-14
Classification:  Random walk,  conditional law,  $h$-transform,  ladder variable,  limit theorems,  60J15,  60G50
@article{1176988497,
     author = {Bertoin, J. and Doney, R. A.},
     title = {On Conditioning a Random Walk to Stay Nonnegative},
     journal = {Ann. Probab.},
     volume = {22},
     number = {4},
     year = {1994},
     pages = { 2152-2167},
     language = {en},
     url = {http://dml.mathdoc.fr/item/1176988497}
}
Bertoin, J.; Doney, R. A. On Conditioning a Random Walk to Stay Nonnegative. Ann. Probab., Tome 22 (1994) no. 4, pp.  2152-2167. http://gdmltest.u-ga.fr/item/1176988497/