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Networks Emerging in a Volatile World


  • George Ehrhardt
  • Matteo Marsili
  • Fernando Vega-Redondo


The paper proposes a model to study the conditions under which complex networks emerge (or not) when agents are involved in a dynamic coordination setup. The focus, however, is not on the classical issue of equilibrium selection - instead, our aim is to shed light on how agents' efforts to coordinate a¤ect the process of network formation in a large and complex environment. The model posits that, over time, new links are created if they are pro.table, and existing links disappear due to exogenous decay. Alongside this struggle between link creation and link destruction, agents' choices in the coordination game adapt to their current local conditions and thus coevolve with the social network. The dynamic behavior of the system is studied within di¤erent time scales (the long and ultralong runs), which di¤er in the role accorded to the noise that is induced by finite populations. We characterize analytically the evolution of the modelin each case and show that, depending on the time scale under consideration, the process displays discontinuous transitions in overall connectivity, resilient transformations in network topology, and equilibrium multiplicity. This behavior is akin to that observed concerning various network phenomena where coordination and network formation display mutually reinforcing roles.

Suggested Citation

  • George Ehrhardt & Matteo Marsili & Fernando Vega-Redondo, 2008. "Networks Emerging in a Volatile World," Economics Working Papers ECO2008/08, European University Institute.
  • Handle: RePEc:eui:euiwps:eco2008/08

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    References listed on IDEAS

    1. Gerard Weisbuch & Alan Kirman & Dorothea Herreiner, 1995. "Market Organization," Working Papers 95-11-102, Santa Fe Institute.
    2. Antoni Calvó-Armengol & Matthew O. Jackson, 2004. "The Effects of Social Networks on Employment and Inequality," American Economic Review, American Economic Association, vol. 94(3), pages 426-454, June.
    3. McKelvey Richard D. & Palfrey Thomas R., 1995. "Quantal Response Equilibria for Normal Form Games," Games and Economic Behavior, Elsevier, vol. 10(1), pages 6-38, July.
    4. Goyal, Sanjeev & Vega-Redondo, Fernando, 2005. "Network formation and social coordination," Games and Economic Behavior, Elsevier, vol. 50(2), pages 178-207, February.
    5. Fafchamps, Marcel & Lund, Susan, 2003. "Risk-sharing networks in rural Philippines," Journal of Development Economics, Elsevier, vol. 71(2), pages 261-287, August.
    6. Hagedoorn, John, 2002. "Inter-firm R&D partnerships: an overview of major trends and patterns since 1960," Research Policy, Elsevier, vol. 31(4), pages 477-492, May.
    7. Manuel Castells (ed.), 2004. "The Network Society," Books, Edward Elgar Publishing, number 3203.
    8. Montgomery, James D, 1991. "Social Networks and Labor-Market Outcomes: Toward an Economic Analysis," American Economic Review, American Economic Association, vol. 81(5), pages 1407-1418, December.
    9. Murgai, Rinku & Winters, Paul & Sadoulet, Elisabeth & Janvry, Alain de, 2002. "Localized and incomplete mutual insurance," Journal of Development Economics, Elsevier, vol. 67(2), pages 245-274, April.
    10. Matthew O. Jackson & Brian W. Rogers, 2007. "Meeting Strangers and Friends of Friends: How Random Are Social Networks?," American Economic Review, American Economic Association, vol. 97(3), pages 890-915, June.
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    Cited by:

    1. Zenou, Yves & König, Michael D. & Tessone, Claudio J., 2014. "Nestedness in networks: A theoretical model and some applications," Theoretical Economics, Econometric Society, vol. 9(3), September.
    2. Mathias Staudigl, 2010. "On a General class of stochastic co-evolutionary dynamics," Vienna Economics Papers 1001, University of Vienna, Department of Economics.
    3. M. Koenig & Claudio J. Tessone & Yves Zenou, "undated". "A Dynamic Model of Network Formation with Strategic Interactions," Working Papers CCSS-09-006, ETH Zurich, Chair of Systems Design.
    4. Staudigl, Mathias, 2011. "Potential games in volatile environments," Games and Economic Behavior, Elsevier, vol. 72(1), pages 271-287, May.

    More about this item

    JEL classification:

    • C73 - Mathematical and Quantitative Methods - - Game Theory and Bargaining Theory - - - Stochastic and Dynamic Games; Evolutionary Games
    • D83 - Microeconomics - - Information, Knowledge, and Uncertainty - - - Search; Learning; Information and Knowledge; Communication; Belief; Unawareness
    • D85 - Microeconomics - - Information, Knowledge, and Uncertainty - - - Network Formation

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