探討地理距離與社會距離對熟識網絡演化的影響

Abstract

我們如何認識我們的朋友?從日常生活的經驗來看，我們的朋友不外乎是因為擁有共同的生活環境或是社交圈有所重疊而產生交集。因此，當人們在選擇互動對象時，應該同時考量地理距離與社會距離接近程度的影響。

本研究利用以下四條規則來進行熟識網絡的動態演化，包括:(1)友誼會受到雙方互動次數及最近兩次互動的時間間距的影響;(2)個體離開後會有新的個體加入;(3)個體會認識新的朋友;(4)個體會和他的朋友互動來維護友誼。我們並且在網絡演化達到穩定狀態後，觀察網絡的拓樸性質。

研究結果發現不管是地理距離或是社會距離都能使熟識網絡演化成具有高群聚度與低分隔度的小世界網絡。此外，社會距離對於群聚現象的影響力高於地理距離，從這項結果可以幫助理解現今的社交網站為何會如此地流行。然而，社交互動媒體只是提供更多維護友誼與結交朋友的方式，在時間、精力等交友資源有限的情況下，大部分的人能夠保持連繫的朋友數都會相似。

How do we make acquaintances? From the experiences of our daily life, we almost have intersections with our acquaintances if we share the same living environment or the social networks are overlapped. Therefore, the effects of the geographic distance and the social distance must be taken into account when people choose their interactive objects. In this study, we use the following four rules to implement the dynamic evolution of acquaintance networks, including: (a) friendships are affected by the times of interaction and the time interval of the last two interactions; (b) a new individual will join the network after the old one leaves; (c) individuals make new acquaintances; (d) individuals interact with their acquaintances to maintain the friendships. Moreover, we observe the topologies of networks when the evolution reaches the stationary state. In the result, we find both the geographic distance and the social distance make the acquaintance networks evolved into small-world networks, which are characterized by higher clustering coefficient and lower degree of separation. Besides, the social distance has a greater influence on the cluster phenomenon than geographic distance. From this result, we can realize why social networking sites are so popular nowadays. However, the social networking sites only supply more ways to maintain friendships and make acquaintances. The number of acquaintances most individuals keep in touch with is similar because of the limited resources, like time, energy, etc.