Systems Engineering FAQ

Answers by Robert Halligan FIE Aust CPEng IntPE(Aus).

Are different states always mutually exclusive? Is there ever a scenario when states would exist at the same time?


The general concept of state allows for concurrency of state, without limitation. However, the benefits of the use of state at a requirements level are maximized to a very high degree by adopting a policy of only defining states that are mutually exclusive, as a starting point, and only admitting concurrency of state if there is clear benefit in doing so. The practical effect of this policy is about 3% of systems or software subject to requirements specification will have any possibility of concurrency of states defined.

An example of states for a smartphone allowed to be concurrent would be a “SIM-Removed State” and a “Battery-Removed State”. These would be mutually exclusive to all the other states (Off, On, Depleted and Failed), which would also be mutually exclusive amongst themselves.


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Published 2 years ago


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