Monotonicity of Recurrence in Random Walks

Rupert Li, Elchanan Mossel, Benjamin Weiss

Published 2024-03-06Version 1

We consider non-homogeneous random walks on the positive quadrant in two dimensions. In the 1960's the following question was asked: is it true if such a random walk $X$ is recurrent and $Y$ is another random walk that at every point is more likely to go down and more likely to go left than $Y$, then $Y$ is also recurrent? We provide an example showing that the answer is negative. We also show that if either the random walk $X$ or $Y$ is sufficiently homogeneous then the answer is in fact positive.