Unformatted text preview: not, provide a short, informal justiﬁcation for why the string cannot be generated. [6 points] 2. What is the language of the grammar? You need not prove your answer, but you should provide a short informal justiﬁcation for your answer. [2 points] 3. Is the language of the grammar regular? Prove your answer. [2 points] Problem 2 . [Category: Design+Proof] Design a contextfree grammar for the language L = { a i b j  2 i ≤ j ≤ 3 i, i,j ∈ N } . Provide a formal proof that your construction is correct. Hint: Build a grammar for the case when j = 2 i and j = 3 i , and think of a way to fuse the two together. [10 points] Problem 3 . [Category: Comprehension+Design+Proof] 1. Solve problem 2.27. [5 points] 2. Read about Post’s Correspondence Problem from section 5.2. Solve problem 5.21. [5 points] 1...
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 Fall '08
 Viswanathan,M
 Formal language, Formal grammar, Contextfree grammar, informal justification

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