Fig. 2
An illustration of the Price model with two edges added per node (m=2) and three fields (F=3) as indicated by the three types of node. Time increases as you move up the diagram so the vertical ordering of the nodes represents a total order in the DAG. Solid (dashed) lines represent citations between papers of identical (different) fields. A new node labelled 16=(t+1) in field 0 (green squares) is added an existing network of fifteen nodes. Here we suggest the two edges added to node 16 are to the two nodes of highest degree (the cumulative advantage bias) with one in the same field (continuous edge) and one in a different field (dashed edge)