Viability and Resilience in the Dynamics of Language Competition

This chapter describes a first case study applying viability based resilience,
presented in Chapter 2, on an individual based model (IBM). A particularly sensitive
issue is to derive macroscopic descriptions from these IBMs, involving a
limited number of variables. Indeed, as explained in Chapter 7, this is the condition
to make tractable the computation of the viability kernel and resilience
values. The chapter introduces Individual Based Models (IBMs) of language
competition, and explores, through computer simulations, the pattern dynamics
of these models and the qualitative role of the prestige and volatility parameters.
Then it proposes several approaches inspired by physics to perform the
derivation of macroscopic descriptions that are able to capture key aspects of the
phenomena observed in the IBMs. Finally, it presents an explicit calculation of
viability and resilience based on a macroscopic description.