How many active states does every region at least need to have in a state machine diagram?

How many active states does every region at least need to have in a state machine diagram?

• A. At least 1 per region
• B. At least 2 per region
• C. At least 0 per region
• D. Exactly 1 per region

Answer: (A)

Regions in a composite state split behavior into parallel dimensions, so when the state machine is in that composite state, every region must contribute an active state. That means there is at least one active substate in each region, giving the minimum of one active state per region. In practice, a valid configuration has exactly one active substate per region at any moment, but the essential idea for the minimum is that no region can be left without an active state. So, with two regions, you’d have at least two active states in total (one in each region).

Regions in a composite state split behavior into parallel dimensions, so when the state machine is in that composite state, every region must contribute an active state. That means there is at least one active substate in each region, giving the minimum of one active state per region. In practice, a valid configuration has exactly one active substate per region at any moment, but the essential idea for the minimum is that no region can be left without an active state. So, with two regions, you’d have at least two active states in total (one in each region).