The persistence of a local dialect when a national standard language is present - a mathematical model

In this presentation, I would like to talk about the research project I have been conducting in Kyushu University. According to the UNESCO Atlas of the World's Language in Danger, several languages are currently in danger of extinction in the world. Particularly, there are many endangered languages in South America, and eight endangered languages inside Japan – Ainu, Amami, Hachijou, Kunigami, Miyako, Okinawan, Yaeyama and Yonaguni languages. One of the reasons for these severe declines is that individuals prefer to speak more powerful languages. In the case of dialects, the existence of a national standard language usually drives individuals to adopt the standard language, especially in public spaces. However, many dialects are still used in more intimate communications, inside family or between close friends. Here, we propose a mathematical model to understand how a local dialect can persist when confronted with a more powerful standard language. In our model, we assume individuals are allowed to choose languages to use in two different contexts: public and private. Our results indicate that dialects attractiveness and how much importance you place on the private dialect influence the persistence of the local dialect.