1. Develop a sequence diagram showing the interactions involved when a student registers for a course in a university. Courses may have limited enrollment, so the registration process must include checks that places are available. Assume that the student accesses an electronic course catalog to find out about available courses.

2. Draw a use-case diagram showing the interactions involved when a customer buys an item from Amazon. Customers need to login first or create an account, then they can search for an item, add it to cart, and process the payment.