Lets say I have the below language:S = {a, b}So if we apply Kleene plus to that language, it is something like:S+ = {a, b, aa, bb, ... ..}   If we apply Kleene plus to above language again, It is something like:(S+)+ = {a, b, aa, bb, aaa, bbb ... ..}What are the best words/way to describe that  (S+)+ = S+?Obviously, S+ is all concatenations of words in S excluding the /\ (the empty string)In this case, (S+)+ is all concatenations of words in S+ excluding  /\So that means (S+)+ includes the words in S+. Is this a good proof?
What is the best way to prove (S+)+ = S+?
formal languages;sets;kleene star