サクワ　ケンタロウ   SAKUWA Kentaro   佐桑　健太郎    所属   青山学院大学  国際政治経済学部 国際政治学科    職種   准教授
言語種別	英語
発行・発表の年月	2025/05
形態種別	学術雑誌
査読	査読あり
標題	Structural Balance of Alliance and Rivalry Networks in International Relations
執筆形態	共同
掲載誌名	Artificial Life and Robotics
掲載区分	国外
巻・号・頁	30,pp.303-309
著者・共著者	Koji Oishi and Kentaro Sakuwa
概要	Does the enemy of my enemy become my friend? A growing body of literature on structural analysis of interstate relationships has tackled this old question from the complex system and network perspective. However, the mechanism of long-term change in the structure of cooperation and enmity has yet to be fully understood. In search for a general explanation for the long-term evolution of interstate structure, we empirically examine the structural balance theory, which predicts that a signed network evolves toward a more “balanced" structure where in many triangular relationships (i.e., triads) two states tend to share a common enemy or three states cooperate with each other. We investigate the network of alliances (positive edges) and rivalries (negative edges) between sovereign states and examine whether its evolution from 1816 to 2009 can be explained by the structural balance theory. We find the consistency with the structural balance theory drastically changes over time. The empirical pattern follows the prediction by the theory before German unification in the nineteenth century and after World War II while being inconsistent in the middle period. This result reveals the impact of the two historical events on the underlying mechanism of network evolution. Moreover, the contrast with previous studies of signed social networks that generally support the structural balance theory indicates that international alliance and rivalry networks can be promising material to study novel mechanisms behind the time evolution of signed networks and complex systems of conflict and cooperation.
DOI	https://doi.org/10.1007/s10015-024-00997-w