159 questions linked to/from How to prove that a language is not regular?
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### Proving a language is regular or non-regular [duplicate]

I'm struggling a bit to understand two of the problems we were given in class. Could someone look over my work and maybe give me a few hints? State whether the following languages are regular or not ...
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### Show that a language is not regular using the Pumping Lemma [duplicate]

Possible Duplicate: How to prove that a language is not regular? Given a language $L = \{a^pb^{2p} \mid p \ge 1\}$, how could I show, using the Pumping Lemma that $L$ is not regular?
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### Can't tell whether the following language is regular or not: [duplicate]

I have to decide if the following language is regular or not. I suspect it is not regular, so I try using pumping lemma to prove it, but something goes wrong. Any help on how to use pumping lemma on ...
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### If there is comparison between two variables then language is not regular. Then how the below two languages L1 and L2 Regular? Please Explain [duplicate]

How these two languages be regular.If there is comparison between m and n since (n < m) is the condition to be satisfied.
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### Show that a language is not regular by Pumping Lemma [duplicate]

Possible Duplicate: How to prove that a language is not regular? Show that $L_2=\{a^nb^k|n\not= k-1\}$ is not regular by Pumping Lemma.
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### Is there a regular grammar for the language $\{ w : |w|_0 = |w|_1 \}$? [duplicate]

I need to prove whether the language $L = \{w \in \{0,1\}^* \mid |w|_0 = |w|_1 \}$ can be written as a regular grammar. Obviously it can, but how do I prove it?
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### $L = \{a^{n^3} | \ge 0\}$ Use the Pumping Lemma to show that L is not regular [duplicate]

Use the Pumping Lemma to show that $L$ is not regular: $$L = \{{a^{n^3} | \ge 0}\}$$ I feel like I have a good intuition of what the Pumping Lemma states; strings that belong to a regular language ...
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### Prove its not a regular language [duplicate]

I have a question. Assume $L = \{ a^m b^m \mid m ≥ 1 \}$ is not a regular language. Prove that $I = \{ a^{5n} b^{3m} c^n d^m \mid m,n ≥ 0 \}$ is not a regular language. I can prove it with pumping ...