Fig. 2

Bow tie model. The bow tie model [34] partitions a network into a strongly connected component (SCC), flanked by IN, where nodes can reach the core but are not reachable from it and OUT, where nodes are reachable from the core but not vice versa. Further components are TUBE, providing an alternative route from IN to OUT and the TENDRILS (TL_IN, TL_OUT) which contain nodes connected to IN and OUT which cannot reach the SCC. Any remaining nodes are collected in OTHER. The colors in this figure correspond to Fig. 3