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One of the earliest classical models alluding to such a program was the classical Segregation model of Thomas Schelling. This model is implemented and described on the Internet Education Project page of the Carl Vinson Institute of Government http://iep.cviog.uga.edu :2000/SIM/intro.htm :

'In the early 1970s, Thomas Schelling created one of the first agent-based models that was to lead to a new view of the underlying causes of an important social indicator. Shelling was interested in understanding why residential segregation between races appears to be so persistent in spite of there occuring a major change in the stated preferences of most people regarding the percentage of other-race neighbors that they would be comfortable living nearby.

Schelling created a simple model in which a given simulated agent (or set of agents) prefers that some percentage of her neighbors be of her own 'color.' If an agent is residing on a square or cell and the agent does not have at least that percentage of her own kind nearby, the agent moves to another square or cell. What Schelling discovered was that even when the agents in the simulation had only a weak preference for nearby agents being of the same 'color', the result after several moves (or chances for each agent in turn to move to another square) was a farily high level of segregation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The basic rule in this model is for agents to keep moving to an available space and to move to the space that has the highest percentage of agents of one's own color. Once one is surrounded by a certain required percentage of agents of one's own type, the agent ceases to move. However, it is often the case that as other agents move to meet their need, even agents who formerly were satisfied with their place/neighborhood will have to move on to another place once one of their like-kind neighbors has move. . . . . . . . .

'What is interesting from a social dynamics perspective is the effect that even a rather slight preference for neighbors of one's own kind can have on the residential segregation of the agents. Sometimes such a slight preference will take a number of moves to take effect. When the agents' preference levels for 'ones own color' become stronger, it will often take a large number of moves for the full segregation effect to play out. . . .

A more modern, developed and sophisticated reincarnation of those ideas is the Sugarscape environment described by Epstein and Axtell in the book "Growing Artificial Societies" (Brookings Institution, 1996.). This model has been widely covered in the media during the recent years, e.g. in the New Scientist of 4 October1997 Giles Wright writes in the article "Rise and Fall":

http://www.newscientist.com/ns/971004/features.html :

In Sugarscape, dots representing people or families move around a digital landscape in search of food--sugar. Whether they live or die depends on whether they find enough food to satisfy their "metabolic" needs. The dots, or "agents", are given a range of abilities--such as how far they can "see" over their virtual landscape when searching for food--and are programmed to obey certain rules. In the most basic scenario, the agents look for the richest source of sugar, and go there to eat it. But they are in competition with each other and with groups of agents programmed with different rules and abilities. By modifying the rules governing how the agents interact, Axtell and Epstein can make them either fight or cooperate. They can allow the agents to accumulate wealth, excess sugar, and measure their "health" by how much sugar they eat. And by introducing mating, the researchers make the agents pass on their abilities--and the rules they obey--to their offspring.

With just a few rules and conditions, the agents in Sugarscape begin to mimic aspects of real life. For example, there is a maximum number of agents that can live in any one model, which depends on the amount of sugar available. This relates to the idea that the Earth has a "carrying capacity"--the density of population it can sustain. When the level of sugar fluctuates between areas--effectively creating "seasons" --the agents migrate from area to area. Axtell and Epstein have also seen the equivalents of tribal formation, trade, and even hibernation. Similarly, extinction, or the end of a civilisation, might be an outcome of the agents following a particular rule. "

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