Recent Progress about Flight Delay under Complex Network

Table 1

Most frequently used topological metrics in air transport network.

Metrics	Equation	Interpretation
Degree [52]		Where mij is the connection between node i and node j: mij = 1 if there is a connection existing; mij = 0 otherwise; this metric refers to the number of connections with other nodes in the network
Betweenness [53]		Where σjk is the number of shortest paths going from node j to node k; σjk(i) is the number of shortest paths going from node j to node k and passing through node i
Average shortest path length [52]		Where N is the set of all nodes in the network, n is the number of nodes; lij [54] is the length of the geodesic from node i to node j, the minimum number of edges connecting from node i to j;
Efficiency [21]
Clustering coefficient [55]		Where is the set of all the neighbor nodes of node i, is the number of nodes ; mik is the connection between node i and node k; this metric gives an overall indication of how nodes are embedded in their neighborhoods