such that the coordination number of a vertex is z = 2n) and periodic boundary conditions (see Fig. 1b). Then each bond is rewired with probability pWS, where rewiring in this context means shifting one end of the bond to a new vertex chosen at random from the whole system, with the constraint that no two vertices can have more than one bond, and no vertex can have a bond with itself. For pWS = 0 the lattice is highly clustered, and the average distance between two vertices hli grows linearly with N, while for pWS = 1 the system becomes a random graph, poorly clustered and hli grows logarithmically with N.