The Impact of Geometry on Monochrome Regions in the Flip Schelling Process

Abstract

11 Schelling’s classical segregation model gives a coherent explanation for the wide-spread phenomenon 12 of residential segregation. We introduce an agent-based saturated open-city variant, the Flip Schelling 13 Process (FSP), in which agents, placed on a graph, have one out of two types and, based on the 14 predominant type in their neighborhood, decide whether to change their types; similar to a new 15 agent arriving as soon as another agent leaves the vertex. 16 We investigate the probability that an edge { u, v } is monochrome, i.e., that both vertices u and v 17 have the same type in the FSP, and we provide a general framework for analyzing the influence of 18 the underlying graph topology on residential segregation. In particular, for two adjacent vertices, 19 we show that a highly decisive common neighborhood, i.e., a common neighborhood where the 20 absolute value of the difference between the number of vertices with different types is high, supports 21 segregation and, moreover, that large common neighborhoods are more decisive. 22 As an application, we study the expected behavior of the FSP on two common random graph 23 models with and without geometry: (1) For random geometric graphs, we show that the existence of 24 an edge { u, v } makes a highly decisive common neighborhood for u and v more likely. Based on 25 this, we prove the existence of a constant c > 0 such that the expected fraction of monochrome 26 edges after the FSP is at least 1 / 2 + c . (2) For Erdős–Rényi graphs we show that large common 27 neighborhoods are unlikely and that the expected fraction of monochrome edges after the FSP is 28 at most 1 / 2 + o (1). Our results indicate that the cluster structure of the underlying graph has a 29 significant impact on the obtained segregation