Classification on the average of random walks

During the last decade many attempts have been made to characterize absence of spontaneous breaking of continuous symmetry for the Heisenberg model on graphs by using suitable classifications of random walks (refs. 4 and 10). We propose and study a new type problem for random walks on graphs, which is particularly interesting for disordered graphs. We compare this classification with the classical one and with an analogous one introduced in ref. 4. Various examples, that are not space-homogeneous, are provided.