Behavioural modelling of long-lived evolution processes - some issues and an example

For reasons now well understood, application software that is regularly used for real-world problem solving must be continually adapted and enhanced to maintain its fitness to an ever-changing real world, its applications and application domains. This type of activity is termed progressive. As evolution continues, the complexity (functional, structural) of the evolving system is likely to increase unless work, termed anti-regressive, is undertaken to control and even reduce it. However, with progressive and anti-regressive work naturally competing for the same pool of resources, management requires means to estimate the amount of work and resources to be applied to each of the two types. After providing a necessary background, the paper describes a systems dynamics model that can serve as the core of a tool to support decision making regarding the optimal personnel allocation over the system lifetime. The model is provided as an example of the use of formalisms in modelling the behaviour of the evolution process