Before revision:  In this paper, we show that the most elementary index, namely the common neighbor (CN) index, is dominated by the leading eigenvector of the adjacency matrix of the target network  .
After revision:  In this paper, we show that the most elementary index, namely the common neighbor (CN) index, is dominated by the leading eigenvector of the adjacency matrix of the target network , with each eigenvector's contribution being proportional to the square of the corresponding eigenvalue. As in many real networks, there is a huge gap between the largest eigenvalue and the second largest eigenvalue, the CN index is thus dominated by the leading eigenvector and much useful information contained in other eigenvectors may be overlooked .