Degree variance evolution operator
Once we know the average degree of a graph, it is possible to compute more complex measures of the heterogeneity in connectivity across nodes (e.g., the extent to which there is a very big spread between well-connected and not so well-connected nodes in the graph) beyond the simpler measures of range such as the difference between k_max and k_min.
One such measure was proposed by the sociologist and statistician Tom Snijders in a paper written in 1981 (Snijders 1981). It is called the degree variance of the graph. It is written v(G) and it is defined as the average squared deviation between the degree degree of each node and the average degree.
See here for more details: Degree Variance
For a temporal graph, the degree variance changes over time.