  We extend our model of wealth segregation to incorporate migration and study
the tendencies towards dual segregation - segregation due to identity (migrants
vs. residents) and segregation due to wealth. We find a sharp, non-linear
transformation between segregated and mixed-wealth states as neighborhood
wealth thresholds become less stringent, allowing agents to move into
neighborhoods they cannot afford. The number of such moves required for the
onset of this transformation varies inversely with the likelihood of agents
willing to move into less wealthy neighborhoods. We also find that this sharp
transformation from segregated to mixed wealth states is simultaneously
accompanied by a corresponding non-linear transformation from a less
identity-segregated to a highly identity-segregated state. We argue that the
decrease in wealth segregation does not merely accompany, but in fact drives
the increase in identity-based segregation. This implies that lowering wealth
segregation necessarily exacerbates identity segregation and that therefore,
this trade-off could to be an important consideration in designing urban
policy. Additionally, we find that the time taken for the tolerance levels of
residents to be breached is significantly lesser under rapid migration. This
rapidity of breach of tolerance could potentially underpin the intensity of
resident responses to sharp bursts of migration.
