An adaptive system, or complex adaptive system, is a special case of complex systems, which is able to adapt its behavior according to changes in its environment or in parts of the system itself. In this way, the system can improve its performance through a continuing interaction with its environment. The concept of complexity in an adaptive system is used to analyze the interactive relationship between the system and its environment, which can be classified into two types: internal complexity for model complexity and external complexity for data complexity. The internal complexity is defined by the amount of input, information, or energy that the system receives from its environment. The external complexity refers to the complexity of how the system represents these inputs through its internal process (He, Jun, 2020)