What are CAS?
According to BusinessDictionary.com, CAS is defined as:
"Entity consisting of many diverse and autonomous components or parts (called agents) which are interrelated, interdependent, linked through many (dense) interconnections, and behave as a unified whole in learning from experience and in adjusting (not just reacting) to changes in the environment." [viii]
One of the most popular definitions of CAS was offered by John H. Holland, a pioneer in the study of CAS:
"A Complex Adaptive System (CAS) is a dynamic network of many agents (which may represent cells, species, individuals, firms, nations) acting in parallel, constantly acting and reacting to what the other agents are doing. The control of a CAS tends to be highly dispersed and decentralized.
If there is to be any coherent behavior in the system, it has to arise from competition and cooperation among the agents themselves. The overall behavior of the system is the result of a huge number of decisions made every moment by many individual agents." [ix]
According to Wikipedia:
Complex adaptive systems are complex in that they are dynamic networks of interactions, and their relationships are not aggregations of the individual static entities, that is, the behavior of the ensemble is not predicted by the behavior of the components. They are adaptive in that the individual and collective behavior mutate and self-organize corresponding to the change-initiating micro-event or collection of events.[x]
The following diagram is a pictorial model of a CAS [xi]:
Figure 3.2: CAS operating model
The preceding diagram depicts the operating model of CAS, at a high level. Self-organizing agents interact with each other, which creates complex adaptive behavior through emergence. The agents receive both positive and negative feedback on their behaviors, which helps them to adjust their behaviors. Moreover, the agents and their behaviors influence and also get influenced by the external environment.