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Anyone could apply some theorem to prove this is not context free? I read lot's of material. it's not homework, it's not exam, it's not anythings. I want to learn, if some people try to answer this question one year later, it's not important, but anyone try to learn me.

$$L_{a}= \{w_{1}cw_{2} : w_{1},w_{2} \in \{a,b\}^{\ast}, w_{1} = w_{2}\}$$

David Richerby
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Prof. Moushi Noura
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    see http://cs.stackexchange.com/questions/19218/is-l-ww-mid-w-in-a-b-context-free or http://meta.cs.stackexchange.com/questions/599/reference-answers-to-frequently-asked-questions/843#843 ... – babou Feb 25 '15 at 08:41
  • @babou, I see both of them, previously, do lots of google search, but I think no one could answer to this explicitly. – Prof. Moushi Noura Feb 25 '15 at 08:48
  • @DavidRicherby, there is no solution. everyone knows how language is not context-free? – Prof. Moushi Noura Feb 25 '15 at 10:33
  • We would like to see what you have tried and where specifically you got stuck after having read and understood the material @babou links. Only then can we determine your issue and help you along. – Raphael Feb 25 '15 at 11:25
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    @Prof.MoushiNoura babou's first link answers the question almost exactly, you only have to stick a $c$ in the middle and do a really tiny amount of alteration to the cases (in fact, essentially none at all). – Luke Mathieson Feb 25 '15 at 11:27
  • @LukeMathieson, I see this on google books. but specifically my example is so hard. – Prof. Moushi Noura Feb 25 '15 at 11:44
  • you are very wrong person @Raphael, I send a massage to moderator to change you. I review lot's of question irrelevant answer of you. – Prof. Moushi Noura Feb 25 '15 at 12:00
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    Everybody here has been trying to help you, in different ways. No one did anything wrong to you. But there are also rules to manage the site. – babou Feb 25 '15 at 12:11

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