Does an activity diagram represent use cases and does it have actors?

Question

I've found an exercise online that shows an activity diagram with some boxes:

And then it asks the following questions:

1. The diagram represents 2 actors each represented by a partition" Possible Answers: "False" "True"

2. This diagram represents the activities of how many use cases?" Possible Answers: "6" "1" "2" "none"

3. This diagram has 2 conditional tests" Possible Answers: "False" "True"

So with this question, I'm wondering if it can represent a use case, and if it does have actors

Answer 1

1. A partition does not necessarily correspond to actors, and every actor does not necessarily correspond to a partition. Moreover Student could correspond to the behavior of a Machine learning component internal to a larger system. So this question cannot be answered with certainty.

   However, assuming that this activity diagram was designed on the base of a use-case and that we can trust the names of the reagion, there would be only one actor: Student , since System would be the subject.

2. Use cases correspond to objectives of the actors and not actions. Moreover a sequence of actions could correspond to a scenario with included or extend use-case and unclear boundaries. Again, we cannot answer this question for sure.

   However, considering that use-cases should be independent and not sequenced, we see that there is only one set of connected activities and one initial node. So if it represents use cases, it would be only 1.

3. This diagram has 2 decision nodes that can each make choices. So the two "conditional tests" do not seem wrong, but it's not UML terminology.

As a side remark, unrelated to your question: The “Select Billets…” activity will never start, because activity diagrams are not flowcharts. Two incoming flows on an activity require both flows to deliver a token before the activity can start. But the rest of the diagram only allows a token to appear on one of the edge, thus leading to a never-ending wait. More explanations here .