Assortativity in Random Line Graphs

We investigate the degree-degree correlations in the Erdoes-Renyi networks, the growing exponential networks and the scale-free networks. We demonstrate that these correlations are the largest for the exponential networks. We calculate also these correlations in the line graphs, formed from the considered networks. Theoretical and numerical results indicate that all the line graphs are assortative, i.e. the degree-degree correlation is positive. (authors)