Saavedra Serguei, Reed-Tsochas Felix, Uzzi Brian
Department of Engineering Science and CABDyN Complexity Centre, Oxford University, Oxford OX1 3PJ, United Kingdom.
Proc Natl Acad Sci U S A. 2008 Oct 28;105(43):16466-71. doi: 10.1073/pnas.0804740105. Epub 2008 Oct 20.
Mechanisms that enable declining networks to avert structural collapse and performance degradation are not well understood. This knowledge gap reflects a shortage of data on declining networks and an emphasis on models of network growth. Analyzing >700,000 transactions between firms in the New York garment industry over 19 years, we tracked this network's decline and measured how its topology and global performance evolved. We find that favoring asymmetric (disassortative) links is key to preserving the topology and functionality of the declining network. Based on our findings, we tested a model of network decline that combines an asymmetric disassembly process for contraction with a preferential attachment process for regrowth. Our simulation results indicate that the model can explain robustness under decline even if the total population of nodes contracts by more than an order of magnitude, in line with our observations for the empirical network. These findings suggest that disassembly mechanisms are not simply assembly mechanisms in reverse and that our model is relevant to understanding the process of decline and collapse in a broad range of biological, technological, and financial networks.
目前对于使衰退网络避免结构崩溃和性能退化的机制尚未完全理解。这一知识空白反映了衰退网络数据的短缺以及对网络增长模型的侧重。通过分析纽约服装行业企业间19年里超过70万笔交易，我们追踪了该网络的衰退情况，并测量了其拓扑结构和全局性能的演变。我们发现，偏向非对称（异配）连接是维持衰退网络拓扑结构和功能的关键。基于我们的发现，我们测试了一个网络衰退模型，该模型将收缩的非对称拆解过程与再生的优先连接过程相结合。我们的模拟结果表明，即使节点总数收缩超过一个数量级，该模型也能解释衰退情况下的稳健性，这与我们对实证网络的观察结果一致。这些发现表明，拆解机制并非简单的组装机制的反向过程，且我们的模型对于理解广泛的生物、技术和金融网络中的衰退和崩溃过程具有相关性。
