Fig. 2.

A toy synthetic NoN generated from two random graph models. Large dotted circles represent Level 2 node groups (originating from isolated NoNs) whose Level 2 nodes are connected in a random GEO- or SF-like fashion. Small solid circles represent Level 2 nodes whose Level 1 networks are of the random graph type indicated. Level 1 nodes and edges are not shown. Level 2 nodes are colored based on their label, i.e. their combination of Level 1 and Level 2 network topology {[(GEO, GEO), (GEO, SF), (SF, GEO) and (SF, SF)]}