Network metrics for science hardness

We adopt concepts from network science in which the networks are first abstracted as undirected graphs.

Metrics	Definition	Metascientific meaning
Degree centrality	The simplest yet most widely used centrality measure is the degree centrality. The degree centrality of a node is the number of direct neighbors the node has.
Betweenness centrality	The betweenness centrality measures the number of times a node lies on the shortest paths between all pairs of nodes in a network.
Clustering coefficient, CC_G	The clustering coefficient of a node represents the proportion of links that exist between its neighboring nodes out of the maximum possible number of links.
Average path length, H_G	Average path length is the mean of shortest path lengths between all node pairs.
Average degree	One of the most commonly used quantities in complex network analysis is the node degree which indicates the number of immediate neighbors of a node.