The owners of a store are looking for a lighted sign that could be mounted outside the store. The lights in the sign should be turned on when the outdoor light level falls below a level defined by the owners. The lights must be turned off automatically at the closing time of 9:30PM.

1. Define the domains.
2. Construct a context diagram and determine the shared phenomena.
3. Define the problem diagram for this scenario.
4. State the requirement(s) in sentence form.