Q1)- What is the relationship between level 0 and level 1 DFD diagrams? Explain.
Q2)- What does Use Case mean? and what does use case describe?
Q3)- What does triggers mean in use case, and what are the trigger types? and who's usually be a trigger?
Q4)- Describe the best way to validate the content of use cases.
Q5)- What is the purpose of an intersection entity? Describe the steps used to create an intersection entity?