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I recently studied about Odgen's lemma and the pumping lemma. I deduced that Ogden's lemma is a general form and was interested: Is there a CFL language by Odgen's but not by the pumping lemma?

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  • $\begingroup$ The answer is already in Odgen's lemma: "Ogden's lemma can be used to show that certain languages are not context-free in cases where the pumping lemma is not sufficient. An example is the language $\{a^ib^jc^kd^\ell \mid i = 0 \text{ or }j = k = l\}$". $\endgroup$ – J.-E. Pin May 25 '18 at 15:07
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For example the language $L = \{a^q 0^n1^m2^p \mid q = 0 \text{ or } n=m=p \}$. We can mark all symbols but the $a$.

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