Unformatted text preview: u  =  v  =  z  , xyuvz ∈ L } . Prove that L may not be regular. Question 2 [4 points] Consider the CFG with rules S → aSbScS  aScSbS  bSaScS  bScSaS  cSaSbS  cSbSaS  ± Does this generate the language { x ∈ { a, b, c } *  n a ( x ) = n b ( x ) = n c ( x ) } where n a ( x ) (respectively n b ( x ) , n c ( x )) is the number of a’s (respectively, b’s, c’s) in string x ? Question 3 [3 points] Describe the language generated by a CFG with rules S → aS  aSbS  ±. Characterize the language by describing a property that every preﬁx of a string in this language must have. Question 4 [3 points] Show using the pumping lemma that the following language is not a CFL: L = { a n b m a n b n + m } . 1...
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This note was uploaded on 12/11/2010 for the course CSE CSE 2001 taught by Professor N during the Winter '10 term at York University.
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