The Matrix Diagram in Visual Paradigm provides a macro view to show the relationships between model elements. This is not limited to model elements having the physical relationship connectors, but also for some more abstract relationships, such as containment, model transitions and even references. Read more
In use case diagram, associations between actors and use cases are explicitly shown. We can see it clearly when an actor carries out a use case (or goal) from a line drawn between them. However, what if an actor does not carry out a use case but do refer to the output from it? How do we model that?