Plane random walk with reflecting barriers. Consider a symmetric random walk in a bounded region of the plane. The boundary is reflecting in the sense that, whenever in a unrestricted random walk the particle would leave the region, it is forced to return to the last position. Show that, if every point of the region can be reached from every other point, there exists a stationary distribution and that u = 1/a, where a is the number of positions in the region. (If the region is unbounded the states are persistent null states and uk 1 represents an invariant measure.) ->