Schelling segregation

One of the major contributions of the economist and game theorist Thomas Schelling was an elegant model of segregation, first described in 1969. The model looks to describe how individuals or particles of different types come to organize themselves spatially into segregated regions, each of largely one type. While the explicit aim was initially to model the kind of racial segregation observed in large American cities, the model turns out to be widely applicable. There are direct links, for example, to the Ising model (used to model physical phase transitions) and to the study of contagion and cascading phenomena in networks. We have now provided a rigorous analysis of the model’s behaviour and have established some surprising forms of threshold behaviour, notably the existence of situations where an increased level of intolerance for neighbouring individuals of opposite type leads almost certainly to decreased segregation.