2014 年 9 巻 4 号 p. 771-789
This paper considers different measures that might become constants for any length of a given natural language text. Such measures indicate a potential for studying the complexity of natural language but have previously only been studied using relatively small English texts. In this study, we consider measures for texts in languages other than English, and for large-scale texts. Among the candidate measures, we consider Yule's K, Orlov's Z, and Golcher's VM, each of whose convergence has been previously argued empirically. Furthermore, we introduce entropy H, and a measure, r, related to the scale-free property of language. Our experiments show that both K and VM are convergent for texts in various languages, whereas the other measures are not.