论文标题
为什么社交网络中有六个分离？
Why are there six degrees of separation in a social network?
论文作者
论文摘要
大量证据表明，现实世界网络具有小世界属性，即，其两个节点之间的最大距离是对数尺寸而不是与它们的大小线性线性缩放。此外，大多数社交网络都是组织的，因此除其他任何一个人之外，没有人超过六个连接，这是一种经验规律性，称为六个分离程度。为什么社交网络拥有这个超小型的世界组织，因此该图的直径与几个数量级的网络大小无关，但仍然未知。我们表明，“六个分离程度”是任何网络的平衡状态所具有的特征，在该状态下，个人在提高中心性的愿望和形成和维持连接所产生的成本之间权衡。此外，我们表明，这种规律性的出现与所有其他功能（例如聚类和规模柔性）兼容，通常会表征社交网络的结构。因此，我们的结果表明，传统上与人类合作和利他主义相关的这种简单的进化规则也可以解释社交网络最有趣的属性之一的出现。
A wealth of evidence shows that real world networks are endowed with the small-world property i.e., that the maximal distance between any two of their nodes scales logarithmically rather than linearly with their size. In addition, most social networks are organized so that no individual is more than six connections apart from any other, an empirical regularity known as the six degrees of separation. Why social networks have this ultra-small world organization, whereby the graph's diameter is independent of the network size over several orders of magnitude, is still unknown. We show that the 'six degrees of separation' are the property featured by the equilibrium state of any network where individuals weigh between their aspiration to improve their centrality and the costs incurred in forming and maintaining connections. We show, moreover, that the emergence of such a regularity is compatible with all other features, such as clustering and scale-freeness, that normally characterize the structure of social networks. Thus, our results show how simple evolutionary rules of the kind traditionally associated with human cooperation and altruism can also account for the emergence of one of the most intriguing attributes of social networks.
