Digraphs are different: Why directionality matters in complex systems

Samuel Johnson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Many networks describing complex systems are directed: the interactions between elements are not symmetric. Recent work has shown that these networks can display properties such as trophic coherence or non-normality, which in turn affect stability, percolation and other dynamical features. I show here that these topological properties have a common origin, in that the edges of directed networks can be aligned—or not—with a global direction. And I illustrate how this can lead to rich and unexpected dynamical behaviour even in the simplest of models.

Original languageEnglish
Article number015003
JournalJournal of Physics: Complexity
Issue number1
Publication statusPublished - 29 May 2020

Bibliographical note

Funding Information:
I have benefitted greatly in my work on this topic from conversations with many colleagues, including Robert MacKay, Bazil Sansom, Nicholas Beale, Richard Gunton, Marcus Miller, Miguel A Muñoz, Virginia Domínguez, Janis Klaise, Serena Di Santo, Nick Jones, Weisi Guo, Charlie Pilgrim and Guillem Mos-quera. I am grateful for the support of the Economic and Social Research Council (UK), through Grant ES/R00787X/1. This was awarded via a call from the Instability Hub of the National Institute for Economic and Social Research (NIESR). I also acknowledge support from the Alan Turing Institute under EPSRC Grant EP/N510129/1.

Publisher Copyright:
© 2020 The Author(s). Published by IOP Publishing Ltd


  • Directed networks
  • Networks
  • Non-normality
  • Percolation
  • Stability
  • Trophic coherence

ASJC Scopus subject areas

  • Artificial Intelligence
  • Computer Networks and Communications
  • Computer Science Applications
  • Information Systems


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