FACING REALITY:Degree distribution of real networks P(A=e<6<k> A Internet Science Collaboration Protein Interactions 10° 10 10 101 10- 101 102 102 103 支102 103 104 103 105 104 ( 10-6 105 104 100 101 102 103 109 10 102 103 100 101 102 k FACING REALITY: Degree distribution of real networks P(k) = e -<k> < k > k k!