Relationship between the in-degree and out-degree of WWW

In this paper, the relationship between the in-degree and out-degree of World-Wide Web is studies. At each time step, a new node with out-degree koutkout is added, where koutkout obeys the power-law distribution and its mean value is m  . The analytical and simulation results suggest that the exponent of in-degree distribution would be γi=2+1/mγi=2+1/m, depending on the average out-degree. This finding is supported by the empirical data, which has not been emphasized by the previous studies on directed networks.