Both the collaboration graph of mathematicians and movie actors were shown to have "small world topology": they have a very large number of vertices, most of small degree, that are highly clustered, and a "giant" connected component with small average distances between vertices.Jerrold W. Grossman. The evolution of the mathematical research collaboration graph. Proceedings of the Thirty-Third Southeastern International Conference on Combinatorics, Graph Theory and Computing (Boca Raton, FL, 2002). Congressus Numerantium. Vol. 158 (2002), pp. 201–212.
