Problem Detail: I’ve been trying to make a CFG, a pushdown automaton and a regular expression for the language $qquad L(M) = {ww : w in {a, b}^*, |w| text{ is even}}$. I understand how the reverse of the string work, that is $qquad L’ = { ww^R : w in {a, b}^*}$, what i am asking for is to do it this way , i have already solved (L’) : http://i921.photobucket.com/albums/ad53/Johann_1990/IMG_20150117_132616.jpg but is there is a way to solve this one too?
$qquad L(M) = {ww : w in {a, b}^*, |w| text{ is even}}$. For example, $abaaba in L$ with $w = aba$.
$qquad L(M) = {ww : w in {a, b}^*, |w| text{ is even}}$. For example, $abaaba in L$ with $w = aba$.
Asked By : AaoIi
Answered By : Raphael
You can not do so as $L$ is not context-free. See our reference questions for how to prove that, i.e.
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Question Source : http://cs.stackexchange.com/questions/37280
