28. Lehman’s Laws of Software Evolution

Remember we did a lesson on configuration management and change management ?
here is an additional element to the same lesson :
Law 1
first law states that system maintenance is an inevitable process. As the system’s environment changes, new requirements emerge and the system must be modified.
Law 2
The second law states that, as a system is changed, its structure is degraded
Law 3
large systems have a dynamic of their own that is established at an early stage in the development process. which suggests that program evolution is largely independent of management decisions
Law 4
Lehman’s fourth law suggests that most large programming projects work in a ‘saturated’ state. That is, a change to resources or staffing has imperceptible effects on the long-term evolution of the system
Law 5
Lehman’s fifth law is concerned with the change increments in each system release. Adding new functionality to a system inevitably introduces new system faults.
Law 6 and 7
When the time passes , new functions need to be added based on operational and environmental demands. ( users of software will become increasingly unhappy with it unless it is maintained and new functionality is added to it)
Law 8
in order to see products improvement, you need to collect feedback and improve accordingly. (it is not yet clear how this can be applied in practical software development)
Summary of Lehman’s 8 Laws


Try this question : 
2016 Sep A2 
a) With respect to Lehman's laws of software evolution, state the two most fundamental laws and explain their implication for software lifecycle management.
(5 marks)