ABSTRACT
System requirements change. Component behaviors change. System structures change. Life by definition changes every day, every moment. Growth or degeneration is the only evidence of life. If one is in the business of modeling and developing abstractions for an artificial system, one has to address this change. Change happens over time. This aspect makes it interesting. Modeling is an art that builds abstractions at the right level of study, and simulation is the mechanism that allows models to display behavior over time. A modeling and simulation framework should be agile to formally specify change and how the system transforms to a new configuration. This is the focus of this chapter.
