Before revision:  The model incorporates the reachability of nodes from anchors and vice versa, captured through multiple random walks. We use random walk since it captures the locality better.
After revision:  The reachability estimations compute the frequency with which a node may visit an anchor through any possible path. The anchors are strategically selected so that the reachability estimations across all nodes are maximized. We show that this combinatorial anchor selection problem is NP-hard and consequently, develop a greedy (1-1/e) approximation.