TOLERANCE OF SCALE-FREE NETWORKS UNDER DEGREE SEGMENT PROTECTION AND REMOVAL
Abstract
We study the tolerance of scale-free networks (following a power-law distribution P(k) = c⋅kα) under degree segment protection and removal. We use percolation theory to examine analytically and numerically the critical node removal fraction pc required for the disintegration of the network as well as the critical node protection fraction ppc necessary to immunize the network against the disintegration. We show that when degree segment protection is prior to degree segment removal and 2 ≤ α ≤3, scale-free networks are quite robust due to the extremely low value of ppc. Meanwhile, if we protect a degree segment with a fixed fraction of nodes, the threshold pc has a generally downward trend as the degree sum of the segment decreases, but it is not strictly monotonic.