{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/emergence-and-evolution-of-hierarchical","title":"Emergence and Evolution of Hierarchical Structure in Complex Systems","arxiv_id":"1805.04924","date":"2018-05-13","proceeding":null,"authors":["Payam Siyari","Bistra Dilkina","Constantine Dovrolis"],"abstract":"It is well known that many complex systems, both in technology and nature,\nexhibit hierarchical modularity: smaller modules, each of them providing a\ncertain function, are used within larger modules that perform more complex\nfunctions. What is not well understood however is how this hierarchical\nstructure (which is fundamentally a network property) emerges, and how it\nevolves over time. We propose a modeling framework, referred to as Evo-Lexis,\nthat provides insight to some fundamental questions about evolving hierarchical\nsystems. Evo-Lexis models the most elementary modules of the system as symbols\n(\"sources\") and the modules at the highest level of the hierarchy as sequences\nof those symbols (\"targets\"). Evo-Lexis computes the optimized adjustment of a\ngiven hierarchy when the set of targets changes over time by additions and\nremovals (a process referred to as \"incremental design\"). In this paper we use\ncomputation modeling to show that:\n  - Low-cost and deep hierarchies emerge when the population of target\nsequences evolves through tinkering and mutation. - Strong selection on the\ncost of new candidate targets results in reuse of more complex (longer) nodes\nin an optimized hierarchy. - The bias towards reuse of complex nodes results in\nan \"hourglass architecture\" (i.e., few intermediate nodes that cover almost all\nsource-target paths). - With such bias, the core nodes are conserved for\nrelatively long time periods although still being vulnerable to major\ntransitions and punctuated equilibria. - Finally, we analyze the differences in\nterms of cost and structure between incrementally designed hierarchies and the\ncorresponding \"clean-slate\" hierarchies which result when the system is\ndesigned from scratch after a change.","url_abs":"http://arxiv.org/abs/1805.04924v2","url_pdf":"http://arxiv.org/pdf/1805.04924v2.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"abstracts"},"code_links":[{"paper_slug":"emergence-and-evolution-of-hierarchical","repo_url":"https://github.com/payamsiyari/Evo-Lexis","is_official":0,"mentioned_in_paper":0,"mentioned_in_github":1,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"syntology_url":null,"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}