Formation mechanisms of local structures in language networks

¹ Department of Information and Computer Sciences, Graduate School of Science and Engineering, Saitama University - 255 Shimo-okubo, Sakura-ku, Saitama-shi, Saitama, 338-8570, Japan
² Department of Management Science, Graduate School of Engineering, Tokyo University of Science 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585, Japan
³ Department of Information and Computer Technology, Faculty of Engineering, Tokyo University of Science 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585, Japan
⁴ International Research Center for Neurointelligence, The University of Tokyo - 7-3-1 Hongo Bunkyo-ku, Tokyo, 113-0033, Japan

Received: 15 March 2019
Accepted: 20 August 2019

Abstract

The small-world property has recently been observed in several language networks generated in terms of word co-occurrence. However, a syntactic interpretation of this universal property has not yet been clarified. This study aims to reveal the formation mechanism of local structures involving small-world properties of co-occurrence language networks. We analyse local structures of language networks with directed edges generated from five different languages, where the directed edges provide word-order information. The results show that the following three syntactic properties play a leading role in the formation of the local structure of a language network: i) agglutination of words, ii) changes in the positions of words, and iii) basic word orders of languages. We further show that a common formation mechanism exists in local structures, even though the syntactic rules vary between the considered languages. These syntactic properties potentially drive the small-world property of language networks.