Give a counterexample to show that the following constructions are not correct proofs for the star operation:
Given a CFG $G = (V,Σ,R,S)$, add the new rule i) $ S → SS$ or ii) $S → SS|ε$.
For i), I basically said that this rule is an infinite loop and doesn't contain an epsilon, so can't be the star operation.
For ii) I'm stuck and can't see why it's not equivalent to the star operation
I know the real star operation is $S'→SS'|ε$ but cant seem to see find out why ii) is not the case. I can't find a counterexample.
Any help is hugely appreciated.