Hello everyone,
Yesterday during the exam (exercise 2) we were asked to prove \( L_1 = \{ a^n b a^n s.t. n\geq 1\} \in CFL \setminus REG \)
The proposed solution (after using P.Lemma) is that \( L_1\) is generated by:
\( S\to aSb| aBb \text{ and } B \to b \)
However, this production \(S\to aBb \to abb\) shows that this generates \( L_B = \{ a^n b b^n s.t. n\geq 1\} \). If I am missing something, please let me know and if that is just a typo, hope that this post will avoid 100 different emails.
