Dismantling the information flow in complex interconnected systems

TL;DR

This paper investigates how damage affects information flow in complex interconnected systems, revealing that structural connectivity alone doesn't predict functional degradation, and proposes a dynamic flow-based damage protocol.

Contribution

It introduces a flow-aware damage protocol that predicts functional fragmentation prior to structural disintegration in complex networks.

Findings

Node removal based on connectivity may have limited impact on flow.

Flow dynamics can be disrupted without structural fragmentation.

Damage protocols considering flow dynamics better predict functional failure.

Abstract

Microscopic structural damage, such as lesions in neural systems or disruptions in urban transportation networks, can impair the dynamics crucial for systems' functionality, such as electrochemical signals or human flows, or any other type of information exchange, respectively, at larger topological scales. Damage is usually modeled by progressive removal of components or connections and, consequently, systems' robustness is assessed in terms of how fast their structure fragments into disconnected sub-systems. Yet, this approach fails to capture how damage hinders the propagation of information across scales, since system function can be degraded even in absence of fragmentation -- e.g., pathological yet structurally integrated human brain. Here, we probe the response to damage of dynamical processes on the top of complex networks, to study how such an information flow is affected. We find that removal of nodes central for network connectivity might have insignificant effects, challenging the traditional assumption that structural metrics alone are sufficient to gain insights about how complex systems operate. Using a damaging protocol explicitly accounting for flow dynamics, we analyze synthetic and empirical systems, from biological to infrastructural ones, and show that it is possible to drive the system towards functional fragmentation before full structural disintegration.