Let L = {a, b}. For the language below, give an example of a string in the language, and a string not in the language.

Question

{w is in L*: uvw = wvu, for some {u, v} in L*}

- To simplify, I would say that any string is in the language if u = w and v can be anything. Would that statement be correct?
-For example, a string in the language would be w = ab, where u = w = ab and v = bb. (But v can be anything as long as it is in L*, right?)(And by "give an example of a string", does the string have to contain more than one character or do "a" and "b" count as strings?)