Cascading processes in complex networks: From systemic risk in banking…

" The term systemic risk commonly denotes the risk that a whole system consisting of many interacting agents fails. We describe it as a macroscopic property that emerges from the nonlinear interactions of agents, quite often via cascading processes in which the failure of a few agents is amplified. For this, we have to model (a) the internal dynamics of the agents, which is largely neglected in other approaches, (b) the mechanisms that spread the failure to neighboring agents in the network. As we will show, details matter to distinguish e.g. the debt relations between banks from contagious deseases, or the friendship relations in an online social network.



The talk provides a general framework for modeling cascading processes in networks, which is illustrated by examples from different areas. In particular, we will present an analysis of online social platforms that allows us to estimate cascades of users leaving, which may eventually lead to the collapse of the platform."