In order to analyze the dynamics of two languages in competition, one
approach is to fit historical data on their numbers of speakers with a
mathematical model in which the parameters are interpreted as the similarity
between those languages and their relative status. Within this approach, we
show here, on the basis of a detailed analysis and extensive calculations, the
outcomes that can emerge for given values of these parameters. Contrary to
previous results, it is possible that in the long term both languages coexist
and survive. This happens only when there is a stable bilingual group, and this
is possible only if the competing languages are sufficiently similar, in which
case its occurrence is favoured by both similarity and status symmetry.Comment: to appear in New Journal of Physic