Abstract
The purpose of this dissertation focuses on the study on the driving forces of dialect diversity. We proposed a model with very weak assumptions, and can derive dialect diversity. Language has many components: vocabulary, grammar, and vocal. This work focuses on the vocabulary since it is the most significant property during the language evolution process. Previous works often proposed some assumptions to increase the isolating force to derive dialect diversity. For example, endow the concept of a village to increase the spatial isolation, and use social marking to increase the social isolation. This work proposed a very simple model with only a few weak assumptions. We let agents who search the best strategy by themselves to evolve in a virtual environment. Agents actually play prisoners' dilemma game and effect their reproduce probabilities. The assumptions in the model are weak, so the degree of freedom is very large. The result of this work shows that, even under a great variance of parameters. Ethnocentric behavior will emerge and derive dialect diversity.