# proving L = {$a^{100}yy^r : \forall y \in$ {a,b}*} is not regular

I need to prove that L = {$a^{100}yy^r : \forall y \in$ {a,b}*} is not regular. i have tried using pumping lemma but couldn't get far with it. Any help in where i should go with it?

• So, what is your question? What did you try (in details)? Where did you get stuck? These should be included in the the OP. Oct 23 '17 at 0:13
• so far i tried using the adversary pumping lemma, let adv pick n and we pick z = $a^{100}a^nba^n(a^nba^n)^r$ im not sure if my setup is correct. Oct 23 '17 at 3:54
• Possible duplicate of How to prove that a language is not regular? Oct 23 '17 at 4:48
• Get rid of the initial part $a^{100}$ by taking an appropriate quotient. Oct 24 '17 at 6:35