Just like there is no absolute definition of "intelligence", there is no absolute definition of "complexity"; the only consensus among researchers is that there is no agreement about the specific definition of complexity.
A simple survey on the model updating methods and correlation criteria is presented.
In this presentation, the entire model updating process is reviewed and some successful methodologies are highlighted.
Based on the author's own experiences over the past 20 years, a number of practical solutions are presented that allowed to remove past barriers, increase user productivity and widen the field of application.
A complex system is thereby characterised by its inter-dependencies, where as a complicated system is characterised by its layers.
Complexity is generally used to characterize something with many parts where those parts interact with each other in multiple ways, culminating in a higher order of emergence greater than the sum of its parts.