“…Intuitively, the central theme behind SimRank is that "two nodes are considered as similar if their incoming neighbors are themselves similar". Based on this idea, there have emerged two widely-used SimRank models: (1) Li et al's model (e.g., [6,8,13,18,27]) and (2) Jeh and Widom's model (e.g., [4,9,11,16,20] Given a directed graph G = (V, E) with a node set V and an edge set E, let Q be its backward transition matrix (that is, the transpose of the column-normalized adjacency matrix), whose entry [Q] i,j = 1/in-degree(i) if there is an edge from j to i, and 0 otherwise. Then, Li et al's SimRank matrix, denoted by S, is defined as…”