We review some studies on complex networks. The complex networks often have structural characteristics: the power-law degree distribution; the logarithmic size dependence of the average path length; and the high clustering coefficient. Several network models with such properties are introduced. We also consider the percolation models on the scale-free networks to show how the critical probability and critical behavior change with network topology.
2011 by the Graduate School of Information Sciences (GSIS), Tohoku University