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Cities As Agents

In the Simpop framework the agents are geographical entities : towns and cities

The level of formalization is then different from most applications of MAS in social sciences. This choice refers to evolutionary urban theory : the hypothesis is that the dynamics of a town or a city depends on its ability to interact with other towns and cities, which in turn depends on its relative situation in the settlement system (in terms of hierarchical level, specialization, accessibility). The city is then seen as a coherent entity, whose potential of growth depends first on its external interactions (core rules of the model) and second on internal specificities (governance). The interurban interactions are the driving forces shaping the emergence and evolution of the system of cities.

Description of the city-agent
  • the agents have three main categories of abilities : to produce, to consume and to exchange. The evolution of a city (decline, stagnation or growth) is a consequence of its ability to succeed in these activities, given the environment and the economico-historical context. The effects of different kind of perturbations can be studied;
  • the agents are autonomous : they handle and apply locally a set of rules referring to these activities and to their consequences in matter of evolution;
  • the agents have knowledge about their environment : they got information on production and demand of the cities with which they are interacting;
  • the agents have the ability to exchange information, goods and wealth. The core of the model is built around two steps : the constitution of the different networks within which the city will exchange; the formalization of the exchanges themselves.
Each city-agent is characterized by several attributes :
  • Localization on a Map
  • Population (reevaluated at the end of each iteration)
  • Wealth (reevaluated at the end of each iteration)
  • Functions port-folio (see below)
  • Supply and demand (amount per function, reevaluated at the end of each iteration)
The type and level of function can evolve through time, depending on the ability of the city to adopt innovations and to become attractive for some dynamic and leading activities.