关键词: 复杂网络, 金融网络, 级联失效模型, 仿真, 可靠性分析

Abstract: Nowadays, with the continuous development of science and technology, society becomes more prosperous, but at the same time, systems in society become more complex. The complex network theory plays an important role in many kinds of network research. With the rapid development of the economy, the development of China’s financial network changes each day. The types of financial institutions and financial products are becoming more diversified, and the relations among financial institutions are becoming more complex, and the structure of the financial network has also become more intricate.In order to reduce the cascading failure of complex financial network and prevent the major systemic financial risks and enhance the invulnerability of complex financial networks, it is necessary to clarify the structural relationship between financial networks, analyze the mechanism of cascading failure of financial networks, and study the reliability of financial networks based on cascading failure model, and then explore the methods to avoid cascading failure of financial networks. Based on the dynamic characteristics and cascade failure mechanism of complex network, financial network and its cascade failure model are established, and the initial loads and capacities of nodes and connecting edges are defined.Then, the reliability of cascade failure model of financial network under different conditions is quantitatively analyzed by simulation, and the result shows that the model is effective, which is helpful for the prevention from the failure of complex financial network and further research into it.
Cascading failures have attracted considerable attention due to their widespread occurrence in various real world systems and their highly destructive effect on network robustness. Although the current research on cascading failures in complex networks is relatively in-depth, it still faces many challenges as the structural and dynamic heterogeneity of real financial systems . This paper focuses on the model of complex financial networks with respect to cascading failures. Cascading failures in complex financial networks can lead to large-scale network collapse and a series of disastrous consequences, but cascading failures can be effectively prevented and solved by modeling, simulation, and quantitative analysis.Based on the complex network theory, this paper establishes the financial network model by using the graph theory language, and then applies the cascade failure model to the study of complex financial network for the first time.Finally, based on this model, we analyze the reliability of financial network and draw the following two conclusions:
(1)In the process of cascading failure simulation of financial networks, increasing the number of iterations will lead to the decrease in network efficiency and the increase in node failure efficiency. When the network is deliberately attacked, the network efficiency will decrease rapidly, the node failure rate will increase rapidly, the network will be greatly impacted, and the impact will be much greater than that in the case of random attack.
(2)Under the same attack mode, improving the risk tolerance coefficient will help to improve the network efficiency, reduce the failure rate, improve the network reliability, and even avoid the occurrence of network cascade failure, but it will pay the corresponding cost.
In addition, the relationship between cost and risk tolerance coefficient is discussed, and it is found that the relative change relationship between α and relative increased cost e is as follows: e=1+α. Finally, this paper puts forward some suggestions on how to optimize the reliability of financial network from two aspects: strengthening the protection of key institutions and taking emergency measures after failure.

Key words: complex network, financial network, cascading failure model, simulation, reliability analysis