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arXiv 2407.08697physics.soc-phphysics.app-phphysics.data-an
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有向符号网络中的链接互惠性模式

Patterns of link reciprocity in directed, signed networks

Anna Gallo, Fabio Saracco, Renaud Lambiotte, Diego Garlaschelli, Tiziano Squartini

AI总结:

本文研究有向符号网络中的挫折与互惠性,将指数随机图框架扩展至二元有向符号网络以量化长度为2环的互惠或对抗倾向,发现平衡理论的有向扩展无法一致解释经验模式,呼吁考虑边方向性的新理论。

摘要:

大多数关于符号网络的分析都集中在平衡理论上,即将挫折(frustration)归因于具有奇数条负边的无向三元基序;对其有向对应物的关注则少得多。为了填补这一空白,我们聚焦于有向符号连接,旨在探索此类语境下的挫折概念。在处理有向符号边时,挫折是一个多面的概念,在不同尺度上允许不同的定义:如果仅考虑长度为2的环,挫折与互惠性相关,即边允许存在指向相反方向伙伴的倾向。由于符号网络的互惠性仍鲜为人知,我们采用一种有原则的方法进行研究,定义相关量并引入模型以一致地捕捉此类经验模式。为了量化经验网络形成互惠或对抗性长度为2环的倾向,我们将指数随机图框架扩展至具有全局和局部约束的二元有向符号网络,随后将上述模式的经验丰度与各模型下的期望丰度进行比较。我们发现,平衡理论的有向扩展无法为本文所研究的有向符号网络特征模式提供一致的解释。尽管部分歧义可通过采用更粗粒度的平衡定义来解决,但我们的结果呼吁一种不同的理论,以连贯的方式考虑边的方向性。无论如何,经验符号网络可能具有高互惠性的证据促使我们建议,在确定更高层次(如三元层次)的挫折时,应明确考虑双向二元组所扮演的角色。

英文摘要:

Most of the analyses concerning signed networks have focused on the balance theory, hence identifying frustration with undirected, triadic motifs having an odd number of negative edges; much less attention has been paid to their directed counterparts. To fill this gap, we focus on signed, directed connections, with the aim of exploring the notion of frustration in such a context. When dealing with signed, directed edges, frustration is a multi-faceted concept, admitting different definitions at different scales: if we limit ourselves to consider cycles of length two, frustration is related to reciprocity, i.e. the tendency of edges to admit the presence of partners pointing in the opposite direction. As the reciprocity of signed networks is still poorly understood, we adopt a principled approach for its study, defining quantities and introducing models to consistently capture empirical patterns of the kind. In order to quantify the tendency of empirical networks to form either mutualistic or antagonistic cycles of length two, we extend the Exponential Random Graphs framework to binary, directed, signed networks with global and local constraints and, then, compare the empirical abundance of the aforementioned patterns with the one expected under each model. We find that the (directed extension of the) balance theory is not capable of providing a consistent explanation of the patterns characterising the directed, signed networks considered in this work. Although part of the ambiguities can be solved by adopting a coarser definition of balance, our results call for a different theory, accounting for the directionality of edges in a coherent manner. In any case, the evidence that the empirical, signed networks can be highly reciprocated leads us to recommend to explicitly account for the role played by bidirectional dyads in determining frustration at higher levels (e.g. the triadic one).

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