Hi, I'm having a little trouble understand the idea of closure as so many places seem to describe it differently. I'm working on an example problem that states "L* is the closure of language L under which relations?" From what I gather, for a language to be closed over a relation, it means that applying that relation to any of its elements results in an element that is also in the language. Is this a correct understanding of the term? Applying this knowledge to that question, I would think the answers are: Union: L U L is in L* Concatenation: LL is in L* Kleene Star: L* is in L* Is this line of reasoning correct, or am I totally missing the mark? Thanks in advance.