UML Diagram

This is a use case diagram about the enrollment of students at a university. There are several flaws in it, and I have to find them.

I am wondering what is happening when you get to use case "Choose course". Yes, you will also have to "Enroll", but what happens if you choose a course that is not available? You will extend the use case, "Course not available", but will you still enroll the course that isn't available? It seems to me like you will.

It would have been different if the association between "Choose Course" and "Enroll" was an extend, because then you only sometimes would enroll in the course, most likely only when it is available.

I am assuming the same logic applies to the "Log-in" use case and the "Student not Identified" use case. You can choose a course without being identified as a student.

  • 1
    "Student not identified" and "course not available" are not really suitable for a use case diagram. Those things belong in some other diagram, like a flowchart. Red Beard's use case diagram below is much better. Commented Nov 10, 2018 at 15:21
  • are you sure you dont want another type of diagram e.g. activity maybe? you seem to be trying to show state transitions?
    – jk.
    Commented Dec 10, 2018 at 14:28
  • Again: Log In is no use case but a constraint that can be applied to use cases. Besides that: don't start functional decomposition with UCs. Recommended read: Bittner/Spence about use cases.
    – user188153
    Commented Apr 3, 2020 at 15:27
  • Intersting that a robot pushes this up the queue again. The OP is pretty much already overseas.
    – user188153
    Commented Aug 1, 2020 at 20:50

1 Answer 1


I am not really sure to understand your use case diagram. What do you want to express? I guess that a Student can "Enroll a Course". To do so, he needs to "Pay fees", "Choose a Course", and "Log-In" right? So the includes links are in the other ways as depicted below. enter image description here

Now to really need to express tha fact that a course is not available? Or a user is not logged? If yes what for?

  • Pretty late for a comment, but your includes go the wrong way around.
    – user188153
    Commented Aug 2, 2020 at 17:35
  • You are right. I updated it. Thanks !!!
    – Red Beard
    Commented Aug 18, 2020 at 8:15
  • I'm always preaching that "Log in" is no use case but a constraint. Seems that's stuck too deeply in people's minds. Alas, the rest is ok.
    – user188153
    Commented Aug 18, 2020 at 8:49

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