What's your use case? - DevLog #002

Some days ago

one of my colleagues asked me, if I can describe NumeRe by its central use case. I really was baffled by this question. How might I describe such a complex application by only one use case, even if it is the central one? Some of you might have experiences with UML and the use case diagrams--most applications do not feature the one and central use case, do they?

I escaped the situation by talking about the complexity of NumeRe and that it's not possible to name its one and central use case. However, this answer was not really satisfiying--neither for my colleague nor for me. Sadly, I was not able to derive a better answer to his question.