Economic Theory

, Volume 30, Issue 2, pp 223–241 | Cite as

Type interaction models and the rule of six

  • Scott E PageEmail author
Research Article


In this paper, I describe and analyze a class of type interaction models. In these models, an infinite population of agents with discrete types interact in groups of fixed size and possibly change their types as a function of those interactions. I then derive conditions for these models to produce multiple equilibria. These conditions demonstrate a trade off between the number of types and the size of the interacting groups. For deterministic interaction rules, I derive the rule of six: the number of agent types plus the group size must be at least six in order to support multiple equilibria given a spanning assumption.


Interactions Multiple equilibria Dynamics 

JEL Classification Numbers



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Copyright information

© Springer 2005

Authors and Affiliations

  1. 1.Center for the Study of Complex Systems, Departments of Political Science and EconomicsThe University of MichiganAnn ArborUSA

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