The Robustness and Vulnerability of a Complex Adaptive System With Co-Evolving Agent Behavior and Local Structure

Agents' irrational behavior would lead to local configuration of complex adaptive system percolation. The corresponding critical point is key to making decisions for improving the system or keeping the system from collapsing. The authors construct a complex adaptive system model where agent behavior and its local configuration co-evolve. This model shows, when an arbitrary agent and its neighbors change their strategy and local interactive configuration, how the properties of percolation critical point of this system would emerge under random attack and intentional attack. It is shown that the system is robust if it is attacked randomly, and there are always at least two large components keeping the system connected. However, if the system is attacked intentionally, the result is more interesting. The system is robust if the deleting probability is smaller than a certain critical probability c0, but the system is vulnerable if the probability is larger than c0. Furthermore, the critical probability c0 is determined by the agent payoff, system structure, and noise.