On harmonic Functions of killed Random Walks in two dimensional convex Cones

Abstract

We prove the existence of uncountably many positive harmonic functions for random walks on the euclidean lattice with non-zero drift, killed when leaving two dimensional convex cones with vertex in 0. Our proof is an adaption of the proof for the positive quadrant from [Ignatiouk-Robert, Loree]. We also make the natural conjecture about the Martin boundary for general convex cones in two dimensions. This is still an open problem and here we only indicate where the proof technique for the positive quadrant breaks down.