# Hierarchical networks

Interactions in many real-world phenomena can be explained by a strong hierarchical structure. Typically, this structure or ranking is not known; instead we only have observed outcomes of the interactions, and the goal is to infer the hierarchy from these observations. Discovering a hierarchy in the context of directed networks can be formulated as follows: given a graph, partition vertices into levels such that, ideally, there are only edges from upper levels to lower levels.

**Project leader(s): **Vicsek Tamás, Palla Gergely

**Participant(s):** Zafeiris Anna, Vásárhelyi Gábor

**Webpage:** hal.elte.hu/~vicsek

**Publication(s):**

- Anna Zafeiris and Tamás Vicsek "Why we live in hierarchies? A quantitative treatise" (Springer, Berlin, ISBN:978-3-319-70483-8) 2018 DOI.