Hierarchical networks

In Chapter 11, we encountered ontologies and phylogenies within the linguistic and genetic context. A hierarchical network builds on the intuition within ontologies and phylogenies; hierarchical networks are tree-like networks that can include multiple sources and sinks flowing from the top of the tree to the bottom of the tree. Gene regulatory networks often follow this hierarchical network structure rather than strictly a tree structure, where multiple sources and sinks do not exist in the network, or an ontology structure, where parent vertices don’t typically exist. Figure 14.6 shows an example of a hierarchical network:

Figure 14.6 – A hierarchical network example where the second layer of the network contains the parents of a vertex in the third layer

Studying gene regulation provides insight into myriad areas of research, including the evolutionary pathways within organ systems or species, the pathologies associated...